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My brain just shut down on me after seeing those equations. yes, would love to see some technical or chemical details about each of the oil groups, especially the POM and PAO based group IV.
keep those infos coming:)

I think this is all good info. However there are always going to be people that will only do what the owners manual explicitly states because they can't formulate a rational logic based thought on their own. What that means is that some people will always continue to use only 5W20 conventional oil even though it's not the best thing for the engine and no amount of proof will change their mind until someone gets Mazda to directly rewrite the owners manual.

I think this is all good info. However there are always going to be people that will only do what the owners manual explicitly states because they can't formulate a rational logic based thought on their own. What that means is that some people will always continue to use only 5W20 conventional oil even though it's not the best thing for the engine and no amount of proof will change their mind until someone gets Mazda to directly rewrite the owners manual.

I understand your thoughts on that, I hoped the fact that Mazda was a member of JAMA, who in turn is a member of ILSAC might bring to light the fact that the initiatives I've shown in this document come partially from the needs of Mazda for motor oil. Fuel economy is the driving force in Mazda's selection of 5w-20 motor oil, they say so in the GF-4 background and in the outline for the new GF-5.

Believe me, I'm all for educating people and getting them to finally see the light. Unfortunately for some people the light at the end of the tunnel is turned off!

My brain just shut down on me after seeing those equations. yes, would love to see some technical or chemical details about each of the oil groups, especially the POM and PAO based group IV.
keep those infos coming:)

Will do...

kinda funny, i just threw in some basic info i got off of my old text book. its in a new thread as well.

but yours have a wealth of information, and very good equations to knock out... had anyone had a specific question that needed answered.

good find, and guidelines to follow.

ok well my brain as well shutdown as eyes popped out of my head after trying to read everything, one of you said 5 20 isnt best for the motor could you tell me what is better for the 8? 5w 30?

ok well my brain as well shutdown as eyes popped out of my head after trying to read everything, one of you said 5 20 isnt best for the motor could you tell me what is better for the 8? 5w 30?

Haha, well like I said I'm planning to do more in depth rotary stuff at a later date. As I'm sure you can imagine, putting all this research together takes awhile.

For now I'd run a group IV 10W-30 like royal purple or amsoil (non XL). With the summer upon us, low temperature startability shouldn't be an issue since we probably wont see temperatures below the mid 60ºF range. However with the high ambient air temperatures and road surface temps we will need good high temp protection. Lets compare Mobil 1 5w-20 (http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil_1_5W-20.asp) and AMSOIL 10W-30 (http://www.amsoil.com/storefront/atm.aspx) . At 100ºC Mobil 1 has a kinematic viscosity of 8.8cSt and AMSOIL has a kinematic viscosity of 10.7cSt; that's a 21.6% increase in viscosity. At 150ºC (HTHS) Mobil 1 has an absolute viscosity of 2.62cP and AMSOIL has an absolute viscosity of 3.2cP; a 22.1% increase. Keep in mind that the viscosity is a measure of the energy required to pull the oil apart, so it'll take 21-22% more load to push the oil film from the internal surfaces of your engine in theory. There are other reasons, but that's for later ;) .

I think my head just exploded!

Great info BMonkey ! I actually read almost all of them when I was studying engine oil on my own. (except for some of the newer stuff)

Hmm, like RG said, there are people, no matter what you do, any kind of facts you have, they simply will never change their mind. (Im thinking, do they pray to Mazda's bible ... I mean the user manual everyday? next thing I know is that "Mazda knows best about rotary engine, do you think they will let you use something that will damage its products?" Yes I think they will. and I already explained my opinion about it before in other post.)

IMO, SM specification is kinda like a *step down* from the older spec. It looks like they come out with something to try to save a few bucks for oil companies.

Look at this thread from RR.
http://www.rx8club.com/showthread.php?t=146186

The wear ... he never said what engine oil was the guy using, I dont think he knows, but from the picture of the wear ... it smells like 5w20.

Did the engine work? yes, if it wasnt the water leak (seals bad), it still runs. damn this reminds me of expo's old motor.

but I do not think the oil is protecting the engine as it should.

Believe me, I'm all for educating people and getting them to finally see the light. Unfortunately for some people the light at the end of the tunnel is turned off!

as opposed to people who stare at the light a bit too long; only seeing bright whiteness and not understanding why nobody else sees it too ... :eyetwitch

*Ahh, I can see the light ...*

A little "Forum Echo Syndrome" going on here, except with the math to "prove" it.

RG, JaxRX8, TeamRX8, myself, and a few others have discussed in the past the political pressures that have lead engineers and the companies for which they work in the directions we see them going. This is the only reason why we have 5W, and probably soon 0W, oils/lubes specified for our engines/drivelines.

Thanks for your diligence, B.;)

Thanks for taking the time to read it. :)

as opposed to people who stare at the light a bit too long; only seeing bright whiteness and not understanding why nobody else sees it too ... :eyetwitch

What if that bright irresistable light is nothing more than a giant bug zapper waiting for us? Hmmm....

dang, wish I'd seen this sooner, been pondering all this for quite a while now, nice work, thanks for the info.

Wow. First off, thank you for all the hard work you put into making this thread.

Next, here in Florida, I rarely see temps below 35F. And that's obviously only at night for a few hours. So it would appear that I'm a prime candidate to bump up in oil viscosity. I am the exact consumer that is being referenced here. I've been using 5W-20 full synthetic since day one. I'll be bumping up to 10W-30 I suppose. Don't know how comfortable I feel going much higher than that. (I simply don't know enough about it) Now if I didn't have all this damn pre-bought 5W-20 lying around the house.:mad:

Best thread in a long time. Thank you for sharing some essential info with the community.

Food for thought: The manufacturer needs to do what they need to do, we the enlightened need to do what we need to do.

Paul.

Canola oil that is.

Haha, well like I said I'm planning to do more in depth rotary stuff at a later date. As I'm sure you can imagine, putting all this research together takes awhile.

For now I'd run a group IV 10W-30 like royal purple or amsoil (non XL). With the summer upon us, low temperature startability shouldn't be an issue since we probably wont see temperatures below the mid 60ºF range. However with the high ambient air temperatures and road surface temps we will need good high temp protection. Lets compare Mobil 1 5w-20 (http://www.mobil.com/USA-English/Lubes/PDS/GLXXENPVLMOMobil_1_5W-20.asp) and AMSOIL 10W-30 (http://www.amsoil.com/storefront/atm.aspx) . At 100ºC Mobil 1 has a kinematic viscosity of 8.8cSt and AMSOIL has a kinematic viscosity of 10.7cSt; that's a 21.6% increase in viscosity. At 150ºC (HTHS) Mobil 1 has an absolute viscosity of 2.62cP and AMSOIL has an absolute viscosity of 3.2cP; a 22.1% increase. Keep in mind that the viscosity is a measure of the energy required to pull the oil apart, so it'll take 21-22% more load to push the oil film from the internal surfaces of your engine in theory. There are other reasons, but that's for later ;) .

Viscosity does not mean everything. Oil flow is the same important. With the thicker oil you won't reach the maximum oil flow at high rpms- The reason is that the oil bypass valve will open earlier in the rpm range because of the thicker oil.
With a higher visc oil (thicker) you will reach earlier the pressure where the bypass open.

and the weaker flow means, that the engine's internal parts cooling will be weaker with the thicker oil. The rotary is a very high rpm (and hot), so I think the best is not to exceed the xx-30 visc. at streetuse.

wow, awesome thread! my head exploded trying to read it.
Will come back and finish up later...

Viscosity does not mean everything. Oil flow is the same important. With the thicker oil you won't reach the maximum oil flow at high rpms- The reason is that the oil bypass valve will open earlier in the rpm range because of the thicker oil.
With a higher visc oil (thicker) you will reach earlier the pressure where the bypass open.

and the weaker flow means, that the engine's internal parts cooling will be weaker with the thicker oil. The rotary is a very high rpm (and hot), so I think the best is not to exceed the xx-30 visc. at streetuse.

If what you said is true, why is the older rotaries with 20w50 can last 200+ K miles without much effort ? and for some "strange" reason, not only Rotary, Im talking about ALL modern engines, the thinner the oil(5w20 nowdays), the *shorter* the engine life ?

If what you said is true, why is the older rotaries with 20w50 can last 200+ K miles without much effort ? and for some "strange" reason, not only Rotary, Im talking about ALL modern engines, the thinner the oil(5w20 nowdays), the *shorter* the engine life ?

Maybe you are right, but I think the secret is in the oil temperature. If you use a thinner oil, than much more important to keep the oil level at the max. than with the thick oil. A lot of people only refill the oil when the lights come on. With a thicker oil is not as much dangerous as with the thinner oil.

Another truth is that you can keep lower the oil temperature with a thinner oil (at high rpms). So it is possible that you can get the same thickening with a xx-30, as the xx-40, if you dríve hard the engine.

*Removed*

Correct me if I am wrong, but I believe the reason the damage was done in the first picture WAS due to inadequate oil film.... however the owner had an internal coolant leak which when mixed with oil would not allow proper protection. Thereby causing damage. It wasn't the owner using 5W-20 and over time proved inadequate causing damage.

I don't disagree with what's being said in this thread. I just think those pictures are being misrepresented.

Agreed firebirdude - I don't see the link between 5W-20 being the standard spec oil on most US cars, and bearing failures. There just is no such data.

Don't you think that any increased wear rate, affecting millions of motors in all areas of the USA, would be fairly obvious?

These oils didn't exist in the 1990's - so any 'experiences' with thin oils before that is invalid.

*removed*

Agreed firebirdude - I don't see the link between 5W-20 being the standard spec oil on most US cars, and bearing failures. There just is no such data.

Don't you think that any increased wear rate, affecting millions of motors in all areas of the USA, would be fairly obvious?

These oils didn't exist in the 1990's - so any 'experiences' with thin oils before that is invalid.

They hide their "proprietary" information relating to actual oil test results. I pasted up all of the ILSAC documents stating that they are making the changes in oil to improve fuel economy and improve emissions equipment life. Look at the dates of the GF-1,2,3 introductions, funny how these new oils came into "favor" along the same timeline. I showed that Ford, our parent company, offers a longer warranty on a turbocharged engine thats recommended to use 15W-40 vs. other vehicles using 5W-20 and 5W-30. If you want more evidence relating bearing wear to viscosity, go to the SAE and shell out some cash and read some tech papers, cause there's tons regarding bearing lubricity.

Agreed firebirdude - I don't see the link between 5W-20 being the standard spec oil on most US cars, and bearing failures. There just is no such data.

Don't you think that any increased wear rate, affecting millions of motors in all areas of the USA, would be fairly obvious?

These oils didn't exist in the 1990's - so any 'experiences' with thin oils before that is invalid.

I've seen pictures of a Renesis rebuild from Japan, the *rebuild motor* was using 5w40. it was I think with 120km on the motor, the bearing has a slight wear, but not as bad as anything I've seen from the us motors. The reason for rebuilding is that they guy is adding a Trust(Greddy) turbo and want a complete rebuild with ceramic seals.

Auto manufactures will never publish any data, cuz they know what 5w20 is all about, yea they will tell people that *to maximize fuel economy*, thats all people care these days, unlike the old days of which people cared about the life of their car more than anything else.

if 5w20 is *as good as the other oil weight* as you said, then why did Mazda recommend 5w30 almost everywhere else just not the US market ? That should tell you something isnt it ?

Keep in mind that many of the Renesis engines that have been rebuilt have suffered from heavy wear on the stationary gear bearings. That's due to inadequate oil film being maintained on the bearing surface which is at the end of the path of oil flow inside the engine. The oil heats up entering the engine and heats up passing through the rotors, and as it does so the viscosity is dropping (oil film thickness dropping).
Re-read your post. You persuaded readers to believe that damage was caused by using low viscosity oil, when in fact it was a coolant leak. End of story. No reason to get hostile. I have been agreeing with this thread since the beginning. Keep up the good sleuth work.:icon_tup:

Re-read your post. You made readers believe that damage was caused by using low viscosity oil, when in fact it was a coolant leak. End of story. No reason to get hostile. I have been agreeing with this thread since the beginning. Keep up the good sleuth work.:icon_tup:

:icon_no2: I didnt make readers do anything.
What is coolant at least 50%? Water.
What is water? an extremely low viscosity fluid.
What happened to that bearing? Water and oil mixed and the bearing didn't maintain adequate oil film to provide lubrication.
Was water mentioned in my post as a theoretical lubricant? Yes.


And thanks for the compliment, I'm sorry I'm defensive but I'd like if the thread doesn't degrade into mind numbing debate.

Ok. How about I edit the word to persuaded?

Where did you even mention the word coolant? You didn't. Where did you say this damage was caused by water mixing with oil? You didn't.

You said low viscosity leads to inadequate oil film.

*picture*

That was caused by inadequate oil film.

I'm off it. See you at the track...:icon_tup:

Ok. How about I edit the word to persuaded?

Where did you even mention the word coolant? You didn't. Where did you say this damage was caused by water mixing with oil? You didn't.

You said low viscosity leads to inadequate oil film.

*picture*

That was caused by inadequate oil film.

I'm off it. See you at the track...:icon_tup: added a description for the picture, just for you ;)

First off, Viscosity and oil flow are directly related. I defined Viscosity as a fluid's resistance to flow. Same thing.

Secondly, the primary function of oil is lubrication. Maintaining adequate oil fillm on the bearing surfaces as temperature increases is much more important than maximum flow. Higher oil flow means that the thickness of the oil film on the internal surfaces in a lower viscosity grade oil is thinner than it would be in a higher viscosity grade at a given temperature. There's a balancing act between cooling and lubricity going on. Theoretically if you just wanted maximum cooling, we could just use water. But water isn't nearly vicious enough of a fluid to provide adequate lubrication. Keep in mind that many of the Renesis engines that have been rebuilt have suffered from heavy wear on the stationary gear bearings. That's due to inadequate oil film being maintained on the bearing surface which is at the end of the path of oil flow inside the engine. The oil heats up entering the engine and heats up passing through the rotors, and as it does so the viscosity is dropping (oil film thickness dropping).

Note: the wear in this picture was in an engine that had a coolant leak. However, for the purposes of illustrating what happens when the lubricant film is inadequate, I believe it is adequate.

1. ..As you wrote, there was coolant problem with that damaged bearing, so that's not related close to oil viscosity.
2. Higher flow means higher separate pressure between the parts, and better cooling. All of this three is working for better protection. With a thicker oil you waste a lot of flow, because the bypass valve will open too early.
You will see higher pressure with the thicker oil, but it will goes away at the bypass valve, the pressure won't make circulate more oil in the engine.
3. 10PSI/1000 rpm and more 10 PSI at every more 1000rpm (20psi/2000) is just enough to separate the parts.
I'm aware of using xxw-20 oil, but I think an xxw-30 oil has a good balance between pressure, flow,cooling, so there is good protection.

I heard that an Formula-1 team use straight 5 weight oil in their engine. Why?
High rpms engine's need higher flow, so there is high separate force between the parts, and high cooling ability.

I think a lot of Renesis bearing problem are because of the low oil level. And if the low oil level meets with a thin oil (xxw-20) many times, there will be problems.

1. ..As you wrote, there was coolant problem with that damaged bearing, so that's not related close to oil viscosity.
2. Higher flow means higher separate pressure between the parts, and better cooling. All of this three is working for better protection. With a thicker oil you waste a lot of flow, because the bypass valve will open too early.
You will see higher pressure with the thicker oil, but it will goes away at the bypass valve, the pressure won't make circulate more oil in the engine.
3. 10PSI/1000 rpm and more 10 PSI at every more 1000rpm (20psi/2000) is just enough to separate the parts.
I'm aware of using xxw-20 oil, but I think an xxw-30 oil has a good balance between pressure, flow,cooling, so there is good protection.

I heard that an Formula-1 team use straight 5 weight oil in their engine. Why?
High rpms engine's need higher flow, so there is high separate force between the parts, and high cooling ability.

I think a lot of Renesis bearing problem are because of the low oil level. And if the low oil level meets with a thin oil (xxw-20) many times, there will be problems.
Wow, everything I posted has been wrong... You've solved the entire issue of oil in rotary engines! All of those companies that produce high performance oils with high viscosity grades, listen up! Ayrton012 has done all your research for you and you should all produce low viscosity oils from now on. Apparently formula 1 is using them, and we all know that formula 1 engines usually run 200,000+miles between rebuilds.

Ok, I'm over it. On a more serious note, I'm not here to break everything down for people to the most simplistic levels possible. If you don't get that a motor oil and coolant are both fluids and both have a viscosity, one obviously lower than the other, but both flow over a surface in a similar manner forming a boundry layer just of varying thickness... then that's fine. You have psychological validation of your own intelligence now, you "corrected" me.


Ok, this time I'm really off it. Sorry for the disturbance. :greenchai

thanks for the info.. threads like this singlehandedly improve the site on the whole..

If what you said is true, why is the older rotaries with 20w50 can last 200+ K miles without much effort ? and for some "strange" reason, not only Rotary, Im talking about ALL modern engines, the thinner the oil(5w20 nowdays), the *shorter* the engine life ?you must be talking about really OLD SA22 (1st gen) and not FC's (2nd gen) or FD's (3rd gen) right?

Wow, everything I posted has been wrong... You've solved the entire issue of oil in rotary engines! All of those companies that produce high performance oils with high viscosity grades, listen up! Ayrton012 has done all your research for you and you should all produce low viscosity oils from now on. Apparently formula 1 is using them, and we all know that formula 1 engines usually run 200,000+miles between rebuilds.

Ok, I'm over it. On a more serious note, I'm not here to break everything down for people to the most simplistic levels possible. If you don't get that a motor oil and coolant are both fluids and both have a viscosity, one obviously lower than the other, but both flow over a surface in a similar manner forming a boundry layer just of varying thickness... then that's fine. You have psychological validation of your own intelligence now, you "corrected" me.


Ok, this time I'm really off it. Sorry for the disturbance. :greenchai

ROFL !!!!!!! lol !!!!!!!!

Epic burn.

Wow, everything I posted has been wrong... You've solved the entire issue of oil in rotary engines! All of those companies that produce high performance oils with high viscosity grades, listen up! Ayrton012 has done all your research for you and you should all produce low viscosity oils from now on. Apparently formula 1 is using them, and we all know that formula 1 engines usually run 200,000+miles between rebuilds.

Ok, I'm over it. On a more serious note, I'm not here to break everything down for people to the most simplistic levels possible. If you don't get that a motor oil and coolant are both fluids and both have a viscosity, one obviously lower than the other, but both flow over a surface in a similar manner forming a boundry layer just of varying thickness... then that's fine. You have psychological validation of your own intelligence now, you "corrected" me.


Ok, this time I'm really off it. Sorry for the disturbance. :greenchaiUh, sorry if I'm off base here, but aren't you both recommending xw-30 oil for the Renesis as is recommended in most other countries without CAFE legislation. The real question for me is posed by those who recommend 10w-40 or even 20w-50 for the Renesis. Whereas others still point out some benefits of lower viscosity oils at higher rpms. See, for example, some of Royal Purple's recommendations for High Performance Automotive Drag Racing:

Import Engines Naturally Aspirated < 7500 RPM XPR 5W20
Import Engines Naturally Aspirated > 7500 RPM XPR 0W10

Domestic Engines - Small Block
Naturally Aspirated < 7000 RPM XPR 5W30
Naturally Aspirated > 7000 RPM XPR 5W20, 0W10

I asked Royal Purple about using heavier 10w-40 or 20w-50 oil in the current Renesis rotary and they would not recommend it:

"The heavier oils will rob you of horsepower, increase operating temperatures, cause metal fatigue, and cause you to consume more fuel. Heavier oils will give you some extra protection, but at what cost? All of our oils will provide the same level of protection, regardless of the viscosity. We are more concerned with the proper viscosity for your application.

A heavy oil lets say is as big as a softball, but the clearances on the motor are designed for a baseball. You can make it fit, but what are you doing to the oil?

We will protect your rotary engine better, even with a lighter oil."

By the way, I'm no expert (hardly!), just trying to learn by listening to both sides of a discussion.

Uh, sorry if I'm off base here, but aren't you both recommending xw-30 oil for the Renesis as is recommended in most other countries without CAFE legislation. The real question for me is posed by those who recommend 10w-40 or even 20w-50 for the Renesis. Whereas others still point out some benefits of lower viscosity oils at higher rpms. See, for example, some of Royal Purple's recommendations for High Performance Automotive Drag Racing:

Import Engines Naturally Aspirated < 7500 RPM XPR 5W20
Import Engines Naturally Aspirated > 7500 RPM XPR 0W10

Domestic Engines - Small Block
Naturally Aspirated < 7000 RPM XPR 5W30
Naturally Aspirated > 7000 RPM XPR 5W20, 0W106

I asked Royal Purple about using heavier 10w-40 or 20w-50 oil in the current Renesis rotary and they would not recommend it:

"The heavier oils will rob you of horsepower, increase operating temperatures, cause metal fatigue, and cause you to consume more fuel. Heavier oils will give you some extra protection, but at what cost? All of our oils will provide the same level of protection, regardless of the viscosity. We are more concerned with the proper viscosity for your application.

A heavy oil lets say is as big as a softball, but the clearances on the motor are designed for a baseball. You can make it fit, but what are you doing to the oil?

We will protect your rotary engine better, even with a lighter oil."

By the way, I'm no expert (hardly!), just trying to learn by listening to both sides of a discussion.
I don't think I've ever seen molecules that are the size of sporting goods....or an engine with clearances so tight that molecules of any weight oil wouldn't be able to slip in. :) I know what they're trying to say, but you gotta remember, asking a company directly is a very grain of salt sort of deal. Are they telling you that because it's true, or because they produce 3 times the amount of lower weight oils and want to sell them? As far as the higher rpm, lower viscosity for Drag Racing ... that's not an application where maximum bearing life and extended operation is considered. They are trying to give you maximum power and a few degrees lower oil temp. Check out some that are going to be used for extended periods at high heat.

Busch / Cup Super Speedway (e.g. Talladega) XPR 10W40, 20W50
Grand AM / SCCA XPR 5W30, 10W40, 20W50

Here's a motorcycle one, but a more direct comparison between short operation cycle and long operation cycle oil usage:

4-Cycle MX / SX XPR 5W20, 5W30

4-Cycle Enduro XPR 10W40

Given the flexing nature of the eccentric shaft under high loads, I think it's very important to maintain a thick oil film in the stationary gear bearings. This is difficult because the oil passes through the rotors before it gets to the bearings, carrying away the heat of the backside of the rotor face and rotor sides. Then to get to the stationary gears it comes out of the rotor gear passing over the side housing that’s carrying the heat from combustion too. So this oil has already absorbed a large portion of heat by the time it drains out through the side and gets to the stationary gear. Then in the stationary gear it has to provide lubrication to the bearings experiencing the highest loads. A difficult proposition indeed…

I don't think I've ever seen molecules that are the size of sporting goods....or an engine with clearances so tight that molecules of any weight oil wouldn't be able to slip in. :) I know what they're trying to say, but you gotta remember, asking a company directly is a very grain of salt sort of deal. Are they telling you that because it's true, or because they produce 3 times the amount of lower weight oils and want to sell them? As far as the higher rpm, lower viscosity for Drag Racing ... that's not an application where maximum bearing life and extended operation is considered. They are trying to give you maximum power and a few degrees lower oil temp. Check out some that are going to be used for extended periods at high heat.

Busch / Cup Super Speedway (e.g. Talladega) XPR 10W40, 20W50
Grand AM / SCCA XPR 5W30, 10W40, 20W50

Here's a motorcycle one, but a more direct comparison between short operation cycle and long operation cycle oil usage:

4-Cycle MX / SX XPR 5W20, 5W30

4-Cycle Enduro XPR 10W40

Given the flexing nature of the eccentric shaft under high loads, I think it's very important to maintain a thick oil film in the stationary gear bearings. This is difficult because the oil passes through the rotors before it gets to the bearings, carrying away the heat of the backside of the rotor face and rotor sides. Then to get to the stationary gears it comes out of the rotor gear passing over the side housing that’s carrying the heat from combustion too. So this oil has already absorbed a large portion of heat by the time it drains out through the side and gets to the stationary gear. Then in the stationary gear it has to provide lubrication to the bearings experiencing the highest loads. A difficult proposition indeed…Thanks for that clarification. But why not go further and recommend 10w-40 or 20w-50? Is it because of the increased heat?

Thanks for that clarification. But why not go further and recommend 10w-40 or 20w-50? Is it because of the increased heat?

Why don't I recommend higher than 10W-30? a few reasons:
1) Not everyone is out flooring their cars everyday, I'm sure alot of people don't even abide by running it to redline everyday. For those people, a high weight oil isn't going to see extreme temperatures like a turbo'd rx8 at the track might see. In that case, a 10W-30 viscosity grade will help ensure decently low temperature startability (the part where alot of wear occurs anyways) and good power/fuel economy retention. There's no point in providing unnecessary protection that's going to sap a little horsepower and a little fuel economy in an engine that's not driven roughly.

2) I did recommend that season be factored into oil changing as well however, so for the summer here in Texas I run 10W-40 and for the winter I use 5W-40. This is pretty dependant on your own area, which is why I showed you all the temperatures in the J300 to reference the kind of temps you see where you live. If you're up in Canada or something, you'd probably want a 0W or 5W oil in winter. Here in Texas it is not uncommon to have 7-8 months with temperatures regularly in the 100ºF range so it's easy to get away with a heavy weight oil.

3) This ties into point #1 but if you drive it like you stole it, run a heavier oil (than my base recommendation of 10W-30) :)

Thanks, BMonkey

Uh, sorry if I'm off base here, but aren't you both recommending xw-30 oil for the Renesis as is recommended in most other countries without CAFE legislation. The real question for me is posed by those who recommend 10w-40 or even 20w-50 for the Renesis. Whereas others still point out some benefits of lower viscosity oils at higher rpms. See, for example, some of Royal Purple's recommendations for High Performance Automotive Drag Racing:

Import Engines Naturally Aspirated < 7500 RPM XPR 5W20
Import Engines Naturally Aspirated > 7500 RPM XPR 0W10

Domestic Engines - Small Block
Naturally Aspirated < 7000 RPM XPR 5W30
Naturally Aspirated > 7000 RPM XPR 5W20, 0W10

I asked Royal Purple about using heavier 10w-40 or 20w-50 oil in the current Renesis rotary and they would not recommend it:

"The heavier oils will rob you of horsepower, increase operating temperatures, cause metal fatigue, and cause you to consume more fuel. Heavier oils will give you some extra protection, but at what cost? All of our oils will provide the same level of protection, regardless of the viscosity. We are more concerned with the proper viscosity for your application.

A heavy oil lets say is as big as a softball, but the clearances on the motor are designed for a baseball. You can make it fit, but what are you doing to the oil?

We will protect your rotary engine better, even with a lighter oil."

By the way, I'm no expert (hardly!), just trying to learn by listening to both sides of a discussion.

Thanks!

Bump

BMonkey,

Are you going to Sevenstock? I'd love to meet you and chat.

Paul.

as opposed to people who stare at the light a bit too long; only seeing bright whiteness and not understanding why nobody else sees it too ... :eyetwitch

Been reading allegories about Caves recently?

Great thread, should be a sticky, imo.

BMonkey,

Are you going to Sevenstock? I'd love to meet you and chat.

Paul.

Tentatively I will be there saturday the 28th, but I haven't gotten plane tickets or anything yet. Just keep an eye out for this guy (sans facial hair) :)

http://i269.photobucket.com/albums/jj60/uswmwd44/a_047.jpg

Tentatively I will be there saturday the 28th, but I haven't gotten plane tickets or anything yet. Just keep an eye out for this guy (sans facial hair) :)

http://i269.photobucket.com/albums/jj60/uswmwd44/a_047.jpg
Cool car, but ... did you maybe think this was the R8Club website instead of RX-8Club? Do you really have an R8 or was that just a test drive. Love that car.

Cool car, but ... did you maybe think this was the R8Club website instead of RX-8Club? Do you really have an R8 or was that just a test drive. Love that car.

I like cars with 'R' and '8' in the name :lol:
Nah, I have a friend with one and he let me take it for the day, this just happens to be one of the most recent pictures of me on my laptop.

I like cars with 'R' and '8' in the name :lol:
Nah, I have a friend with one and he let me take it for the day, this just happens to be one of the most recent pictures of me on my laptop.

Can you introduce me your friend? so I can lend his R8 for a day as well? lol :lol:

I think this is all good info. However there are always going to be people that will only do what the owners manual explicitly states because they can't formulate a rational logic based thought on their own. What that means is that some people will always continue to use only 5W20 conventional oil even though it's not the best thing for the engine and no amount of proof will change their mind until someone gets Mazda to directly rewrite the owners manual.

this being said, RG, what is the grade of oil that you use in your renesis?

I don't have a Renesis. I have an '84 13B. I have run everything in it from 20W50 to straight 30W to 5W20. Engine runs fine. I'm back up to 10W30 at the moment but since the car is taken apart it's really a moot point anyways.

so what oil are you guys running or reccomend using?

so what oil are you guys running or reccomend using?If I lived in southern California, I would probably use 10w-40 year round like I do in the summer time here in NJ. In the winter I'll use 5w-30, like Mazda recommends in most of the world. In the US, they recommend 5w-20 because of CAFE fuel economy fines. Use high quality oil. Synthetic is best.

If I lived in southern California, I would probably use 10w-40 year round like I do in the summer time here in NJ. In the winter I'll use 5w-30, like Mazda recommends in most of the world. In the US, they recommend 5w-20 because of CAFE fuel economy fines. Use high quality oil. Synthetic is best.

Oh no you didnt say that ! Synthetic is evil ! As soon as you put Synthetic in there your engine gonna blow up within 10 miles ! :lol: :lol: :lol: :lol:

I've been using Synthetic oil (true one that is) for like 41K miles. so how many times did my engine blow up? you do the math :lol: :Eyecrazy:

Oh no you didnt say that ! Synthetic is evil ! As soon as you put Synthetic in there your engine gonna blow up within 10 miles ! :lol: :lol: :lol: :lol:

I've been using Synthetic oil (true one that is) for like 41K miles. so how many times did my engine blow up? you do the math :lol: :Eyecrazy:That would be at least 4,100 times.

Jeez this discussion(not slamming this good info now) has been going on since 1/1/04. the first time i changed the oil in my car i knew damn well it was not providing the protection I wanted. It looked like wd 40 coming out. and yes i have been around awhile--i remember helping my Dad rebuild a flat head ford v/8--it was the families truck etc.
hell this engine cant even maintain the factory recommended oil pressure with 5/20W in it! Yall use some common sense here! Nothing complicated about this.
. I think the bearing wear that has been showing up has to do with something else than just the oil viscosity.
olddragger

Jeez this discussion(not slamming this good info now) has been going on since 1/1/04. the first time i changed the oil in my car i knew damn well it was not providing the protection I wanted. It looked like wd 40 coming out. and yes i have been around awhile--i remember helping my Dad rebuild a flat head ford v/8--it was the families truck etc.
hell this engine cant even maintain the factory recommended oil pressure with 5/20W in it! Yall use some common sense here! Nothing complicated about this.
. I think the bearing wear that has been showing up has to do with something else than just the oil viscosity.
olddragger

but when you look at mysql's motor, he does not have the kind of bearing wear like most pictures we've seen (so far)

it has something to do with viscosity.

When you consider the change in the oilsystem internally for the facelifted RX-8, and the fact that other territories recommend 5W30, which isn't for cold temperature tolereance obviously, it's thicker oil at operating temp. Then you gotta be a bit naive to be putting 5W20 in there. In my opinion. But many people in the US seems to be a bit warrantyscared, so I guess you can't blame them.

When you consider the change in the oilsystem internally for the facelifted RX-8, and the fact that other territories recommend 5W30, which isn't for cold temperature tolereance obviously, it's thicker oil at operating temp. Then you gotta be a bit naive to be putting 5W20 in there. In my opinion. But many people in the US seems to be a bit warrantyscared, so I guess you can't blame them.

Nah, its not warranty scared. its more like this :

"Mazda is the one who created this engine, what makes any of you think that you actually know more than Mazda engineers ? Do you think they will recommend something that might damage the engine in the long run ? 5w20 will work just fine"

maybe their fanbelts were just on too tight.:)
OD

Thanks to all of you for the education on oil. I live in the mountains west of Colorado Springs and we don't get the hot days of Texas, so I always thought the 5/20 was the best. Also the dealer said not to use synthetic and I listened.
I've got 100K on my 04. Looks like I need to change to 5/30. Any particular brand you recommend?

Royal Purple's good without being tooo expensive.

^^^ I plan on changing to that.

have u guys ever heard of synthetic supposedly burning diffrently than mineral based oils? i have heard (dont know if it true or not) that synths dont burn well since oil in rotarys spend a whole lot more "time" in the actual combustion chambers than in piston engines. also what is the max psi that the renisis allows along the lines of oil?

Hey guys. After reading all this info on oil my head is spinning, but if I even retain 10% of this stuff I'm way better off than I was before.

If I might give some of you guys the newbie perspective: I've always been a computer hardware guy, never a car guy. The only things I know about engines and fuels and oils is the very basic stuff I picked up from an intro to piston engineering course while I was learning to fly. I basically have no point of reference.

I was going to put 5w20 oil in my car, not because I refuse to see the light at the end of the tunnel, or because I'm "warranty scared", or because I'm naive. I was going to do it because it's what the manual said to do and it was the only readily available source of info. This place is a treasure trove on information to be sure, but for someone new it's hard to sort out the guys who have the experience and the knowledge from the guys parroting something someone told them once. I'm obviously ignorant of the ways of the world, but I'm trying to learn :)

Now, that being said, I need some help. After much researching and deliberation I bought a 2006 RX-8 GT (MT of course) and I love it. Unfortunately the guy I bought it from left the fluids in a sorry state, and the oil is at a level I would consider uncomfortably low.

You know when you were a kid and you were learning to do something, like your multiplication tables, or playing a sport or anything? Someone who was good at it just told you what to do. You didn't understand why it worked, it just did. Later on when you'd been doing it for a while you understood the wisdom of their words. That's what I need right now. I've got a car that needs oil now, and just enough knowledge to be dangerous.

If one of you smart guys could shed some light on this for me I'd be really grateful. Help me do the right thing for my shiny new car, and I promise to keep learning about these things and pass the knowledge along to some other wide-eyed noob when the time comes :)

I would buy a name-branded 5w20 or 5w30.

Oil has developed a lot in the last few years, and the new specs are almost impossible to meet without including some synthetic components to beef up the blend. If the numbers start with a '5' you are getting the latest formulations.....

10w30 is also a fine grade, but a 10w30 oil can be made mostly from dead dinosaurs, with few of the additives that will keep the oil in-grade and on-spec. Don't buy it unless you are confident in the reputation of the manufacturer....


S

You know when you were a kid and you were learning to do something, like your multiplication tables, or playing a sport or anything? Someone who was good at it just told you what to do. You didn't understand why it worked, it just did. Later on when you'd been doing it for a while you understood the wisdom of their words. That's what I need right now. I've got a car that needs oil now, and just enough knowledge to be dangerous.

Here's an easy answer -- trust in "the wisdom of crowds". What I mean by that is, Mazda recommends 5w30 for this engine in *most* parts of the world. That's really what formed my opinion early on.

Lately we have seen some engine teardowns that suggest going even higher might help. What I decided for myself is that I will change with 5w30, and top-off with 0w40 when low. Mobil1 synthetic in both cases. I figure this helps counteract fuel dilution and viscocity breakdown to keep the oil from being thinned in between changes.

Keep in mind, the recomended oil is for fuel economy. It will get you by, but its not ideal IMO. Check a european or japanese manual to see what those recomend, most likely different than here.

Not sure why you are running 0W anything is Cali Nubo....

"No oil is thin enough at startup...." Dr. A.E. Haas

Zero weight oil is still WAYYY thicker at cold startup than when circulating at operating temperature - so why not run it?

There is NOTHING wrong with the '5' weight oils - and Mr. OutGuy is only partially wrong this time - fuel economy is only one of the MANY benefits of these thinner oils; faster hydraulic film forming, faster warm-up, better heat removal, faster circulation with lower back pressure, less filter differential and shorter filter bypass periods.


S

Hey guys. After reading all this info on oil my head is spinning, but if I even retain 10% of this stuff I'm way better off than I was before.

If I might give some of you guys the newbie perspective: I've always been a computer hardware guy, never a car guy. The only things I know about engines and fuels and oils is the very basic stuff I picked up from an intro to piston engineering course while I was learning to fly. I basically have no point of reference.

I was going to put 5w20 oil in my car, not because I refuse to see the light at the end of the tunnel, or because I'm "warranty scared", or because I'm naive. I was going to do it because it's what the manual said to do and it was the only readily available source of info. This place is a treasure trove on information to be sure, but for someone new it's hard to sort out the guys who have the experience and the knowledge from the guys parroting something someone told them once. I'm obviously ignorant of the ways of the world, but I'm trying to learn :)

Now, that being said, I need some help. After much researching and deliberation I bought a 2006 RX-8 GT (MT of course) and I love it. Unfortunately the guy I bought it from left the fluids in a sorry state, and the oil is at a level I would consider uncomfortably low.

You know when you were a kid and you were learning to do something, like your multiplication tables, or playing a sport or anything? Someone who was good at it just told you what to do. You didn't understand why it worked, it just did. Later on when you'd been doing it for a while you understood the wisdom of their words. That's what I need right now. I've got a car that needs oil now, and just enough knowledge to be dangerous.

If one of you smart guys could shed some light on this for me I'd be really grateful. Help me do the right thing for my shiny new car, and I promise to keep learning about these things and pass the knowledge along to some other wide-eyed noob when the time comes :)

go with something like 5w30 name brand u should be ok. like Stealth has said, some of the w30 oil these days are not really true Full Synthetic (if thats what u're looking for) so you should read the spec before you buy them

True Full Synthetic (GRP IV or V)
Castrol Syntec 0w30 (Notice, their 5w30 is NOT a true Full Synthetic oil)
Some Mobil1 w30 (depends on location, check the box)
Royal Purple 5w30 (GRP IV)
Red Line xw30 (they use GRP V)

I use 10w40 right now. Thinking of going for 5w50, but they use so much modifiers to make such wide grade oil and thats something I am not very comfortable with. but I dont know, I know Ford GT use 5w50 so maybe its ok to use? Im gonna stick with 10w40 for now.

I've been using Mobile1 Supersynthetic 5w-20 and I'm currently living in Southwest Oklahoma. It gets into the 100s in the summer and below freezing often in the winter. Should I keep the same brand and bump up to 5w-30 or change to Royal Purple or something?

hey i recently purchased an 04 rx8 i LOVE it! even though its my first car (im 17 ), i dont know much about the TRUE difference between the synthetic oil and the regular i have been looking and reading forums and i put 5w-20 royal purple (but again im a noob) and i would like to know if i should change it asap to 10w-40 or 5w-40 like bm said( i also live in Tx)

I'm in the same boots as CaptainCanada... Any tips or FAQs on switching to synthetic? My car is still pretty new and ~1,700 miles. Almost time for an oil change and I'd like to put the right oil in it during the first change. Is there a procedure for switching from regular to synthetic oil?

I'm still confused about whether or not synthetic oil is OK for the rotary. Half of you guys say its good, half say its not. I know Idemitsu is a reputable brand and they only make synthetic oil for rotaries...

Way more than half will tell you synthetic is good, in fact it's better, but it's not necessary. Is it worth the extra money--only you can answer that question for yourself.

No special tips on switching to synthetic.

A new owner might not know that about half the oil stays in the oil coolers, so each time you change, you only get about half of the old stuff out......


S

A new owner might not know that about half the oil stays in the oil coolers, so each time you change, you only get about half of the old stuff out......


S

Thats why you HAVE to change the oil every 2500 miles. The system holds 7 quarts and only about 4 are changed if the car is level during the drain. Some people have taken to lifting up each front corner to get the oil out of the coolers, but some will always stay.

The best advantage of running a GOOD synthetic over a GOOD fossil base is that the synthetic won't break down as fast. They might offer better protection depending on the additives, but thats brand dependent. So for MOST of the drivers out there, a GOOD regular oil is more than sufficient. And yes running 5w-30 is the lowest you want to go if this is a daily driver and not just a pure track machine.

Changing the oil every 2500 miles negates a lot of the advantages of running a synthetic since synthetics typically last a lot longer than fossil base.

There are other things to consider. How hard you drive the car? Do you do proper warm up and cool down? Do you live in an area where you get large temperature swings throughout a day?

A big factor in oil breakdown, especially fossil base, is water condensation. Water can collect in the oil if you dont get the oil nice and hot for an extended period of driving. Short trips to the store or to work without getting the engine and oil nice and hot will result in extra moisture collection in the oil, preventing it from doing its job and also breaking it down faster. Large swings in temperature can also lead to extra moisture collecting in the oil.

So for those that do the short trips frequently, it is good to take the car out once a week and flog the living hell outta it for half an hour.

I found a document that has excellent information on oil and how its labeled and tested. I will try to track it down and share it.

[edit]
http://www.zag.si/~jank/public/bmw/oil_bible.pdf

a lot of good information here; thanks to those who put in so much time to help others.

i get my oil changes done pretty religiously by my dealer here. i don't have a house/driveway to do it myself, and just haven't taken the time; so i swing by and have them do it. anyway, i assume they stick to 5w20, like the manual says, but i don't know for sure. so, my question is, if mazda changes my oil...if i want to top it off, will a different type or brand adversely affect my engine? i just topped it off w/ castrol 5w20, but in the future i'd like to try something else. is it bad to have a "mix" of 2 different types of oils at the same time? does that make sense? i don't want to top off w/ something else if it's bad, i'd rather just stick to what mazda is using until i start handling the entire process myself...

and yes, if you're wondering, this is the first time in 5 years i've topped off the oil myself!! ha ha. i've always just gone to mazda and gotten it done right away (sometimes less than 3000 miles). i don't have time to go in the coming weeks so i thought it'd be good to top it off...

Don't worry about mixing. But the amount that you top off, compared with the full capacity of oil, is not enough to matter much what you choose to top off with.

thanks robrecht. that makes sense. i want to try the royal purple on racingbeat's site...it's expensive though!

That you might not want to top off your dealer's oil change with. Royal purple is going to be at the other end of the spectrum from what the dealer uses. It would be a waste. Now if you ran all Royal Purple, then it would be different. You can request certain types of oil and different weight to be used at your next oil change at the dealer. They may give you this stern warning about warranty, its crap. You can put a different brand and weight in and still be covered by warranty.

So if you are concerned, next oil change, bump up to what you think is appropriate based on your local climate and driving style, and request the dealer to put that in. You may pay more for different brand and weight, but its usually worth it. Also when switching weights or brands (if there is a big difference in quality) you may want to have the next oil change at 1000 or 1500 miles instead of the 2500-3000 range as only 4 qts of the 7 are changed.

I got free oil changes for life from the dealer I purchased mine from. Thought it was a great idea til I found out they are using quaker state 5w20. Complete crap oil. I now do all the oil and filter on my own. I store my car for the winter so it doesn't see very cold temps, but usually run 10w30 early spring and late fall and run 10w40 during the summer. Its wisconsin but it can still get really hot up here on the pavement.

I used Idemitsu brand on my rx7 and found that oil to be amazing. Its specially designed just for a rotary. So its synthetic and about the same cost as royal purple. But found it was worth every penny. Also, Idemitsu makes a rotary premix which may be something you might want to look at. Even if you have an aftermarket tune with increased oil flow to the seals, a little premix is added protection. And the stuff is meant to burn clean with no ash (from the research i've done it goes way beyond the TC-W3 rating for 2stroke oils).

The only thing that really stands out about Idemitsu over other oils is the extremely high levels of Molybdenum which is an antifriction agent. That's the good news. The bad news is that at the levels they have it at (over 1000ppm), it has a tendency to fall out of suspension over time. It was only intended to be used in their race cars such as the 787B where the oil never sat around and the oil was only used for hours at a time. It was never intended for a street car for the above reason. Incredible it may be but I won't use it on a street car. That's just me though.

The only thing that really stands out about Idemitsu over other oils is the extremely high levels of Molybdenum which is an antifriction agent. That's the good news. The bad news is that at the levels they have it at (over 1000ppm), it has a tendency to fall out of suspension over time. It was only intended to be used in their race cars such as the 787B where the oil never sat around and the oil was only used for hours at a time. It was never intended for a street car for the above reason. Incredible it may be but I won't use it on a street car. That's just me though.
Is that also true of their premix? If so, could that help explain the problems some people have experienced with fuel screens/filters?

The only thing that really stands out about Idemitsu over other oils is the extremely high levels of Molybdenum which is an antifriction agent. That's the good news. The bad news is that at the levels they have it at (over 1000ppm), it has a tendency to fall out of suspension over time. It was only intended to be used in their race cars such as the 787B where the oil never sat around and the oil was only used for hours at a time. It was never intended for a street car for the above reason. Incredible it may be but I won't use it on a street car. That's just me though.


True, but the 7 was driven daily, multiple times per day. And oil changed religiously before 2500 miles. So that made a difference for me and my driving habits.

It's definitely a very good oil. I've even met the main guy behind it's formulation. He just so happens to be the head of Mazda's rotary engine department! Very low friction as a result of the moly in it. I just won't use it though. Anything that can fall out of suspension can also potentially have issues burning off aka carbon. Mazda did not meter engine oil into their race cars and race cars is what this oil is designed for. Fortunately today there is a wide assortment of very good oils out there.