Good technical discussion about Engine Oils
07-21-2009, 12:53 PM
#51
Registered
The rotary is unique compared to a piston engine. It doesn't mean this info is any less relevant though. The rotary uses the oil as a coolant to a far grater extent than a piston engine does. Therefore our oil inside the engine itself probably hits hotter peak temperatures. We know we have to cool it well as most piston engines don't even have oil coolers yet we struggle with having enough. Racing Beat has mentioned that oil should not exceed 205*F when ENTERING the engine. That's probably due to the amount of heat it picks up while inside the engine. Unfortunately we can't monitor oil temperature at the bearings vs the oil temp inside of the rotors. That's actually OK though as the hottest oil is through the rotors. It is also it's thinnest here which means it flows out easily. The downside is that through the rotors is where the oil typically gets foaming induced. Piston engines typically get it (windage) from the crankshaft spinning through the oil pan. While in the rotors, the oil is not being used as a lubricant anymore. It's a coolant. Unfortunately foaming reduces heat transfer. A thicker oil that flows slower will not foam up as bad but a thinner oil can flow more and remove more heat at a penatly of a higher risk of foaming. It's all about balance. Keep in mind foaming has alot to do with formulation as the viscosity example is a generalization. Oil through the bearings doesn't come through the rotors first. That's a good thing. It's away from any foaming. All of this hot oil from the bearings and much hotter oil from the rotors mixes together in the oil pan and we must cool it back down and get the air out of it.
Also notice that rotaries typically run higher oil pressures than most piston engines. As he notes, a pressure increase is generally a flow increase. While this wouldn't be true with a centrifugal pump, the oil pumps are constant displacement driven off of a chain from the crank so in a perfect world this would hold true. As he notes, we also have oil pressure bypass valves. It has been set at different levels over the rotary years. It comes down to a rotary needing more oil flow through the engine. This is due to the necessary cooling of the rotors from the oil.
We also have the same needs as a piston engine in terms of bearing lubrication. The amount of lubrication needed on a bearing isn't as much as people think it is. Jeff (MM) found and has preached about restrictor pills in turbo oil lines and has noted that it really takes very little total flow to keep them happy. All that matters is that there is sufficient oil flow to keep the bearings lubricated. As the author pointed out, if you run higher oil pressures, you are just wasting horsepower. He never said that you'd damage your bearings. He did say that you would from a lack of flow though. This is where the balancing act of viscosity comes into play.
Keep in mind our bearings receive plenty of oil flow although in a stock engine the flow between the front and rear bearings is not equal which has led some to use different bearings between them. We run excess pressures to increase cooling oil flow through the rotors, not to protect the bearings. We have additional concerns that a piston engine doesn't have.
Finally we have oil being sprayed into the intake to lubricate the apex seals. This is what is responsible for more Renesis failures than anything. It's not the viscosity of the oil itself. The RX-7's had more oil metering flow than the RX-8 does and it was more directed to the center of the apex seals. The 3rd gen RX-7s only had the 2 nozzles in the rotor housings. One in each, direct center. The earlier carbed cars had them dump into the intake manifold and the 2nd gen RX-7's had nozzles in the lower manifold and in the rotor housings. Apex seals were much better lubricated in the pre RX-8 cars and hence engine failures were lower.
The RX-8 introduced 2 metering jets per rotor housing for a total of 4. Up from the 2 in the 3rd gen RX-7 and equal to those previous. However all was not equal. They pointed outwards towards the corners of the apex seals and not at the center. The center receives very little lubrication. However the center of the apex seal is the hottest part as the bending moment of the seal is at it's greatest here and so are the forces holding it to the rotor housing. This area of the seal needs lots more lubrication yet isn't getting any. This causes higher wear on the housings and the seals in this area which leads to lower compression, mileage, and power. Since each engine is different, it also causes different cars to dyno different power levels and get differing mileage numbers from others. None of this has anything to do with oil viscosity.
Viscosity does come into play though. A thicker oil will flow slower which will be less flow per time through the oil metering system. This is less lubrication to the apex seals. Bad news. While the older rotaries did run thicker oil, they also had better oil metering systems that took that oil where it needed to go. It doesn't matter how good your oil is. If it can't get to where it's needed the most, it won't do any good. That's what's wrong with the RX-8's. That is, until the '09s came out. A 3rd metering jet was added to each rotor right where it was needed. In the center of the housing over the center of the apex seal. You'll find these cars will be more consistent with one another in power and economy than the pre '09 cars will. They should have longer engine life too. The best thing a pre '09 owner can do is premix! Then of course we get into a whole new world of issues but I'm not dealing with them here.
As you can see engine oil has a larger role in a rotary engine than it does in the average piston engine. We are harder on it. It goes through greater temperature extremes and is required to do several different things. Because of this, we also need to base our oil choices on more severe requirements. The downside is that we make more compromises as what is best for oil cooling is not necessarily the best for bearing lubrication. What is best for bearing lubrication may not be the best for oil metering. This is why I prefer the Sohn adapter. It takes one thing out of the equation and allows you to run the best oil for metering while leaving the best for the rest of the engine.
Hopefully what I've just explained can help shed some light on reliability issues of the Renesis vs earlier rotary engines. It's not the oil! It's the oil metering system! I am not going to comment definitively on the weight issue though as there have been some signs that a thinner oil does lead to excessive bearing wear while a thicker oil doesn't. However there are also those that haven't found that to be the case. I think only time and more testing is needed in this area and unfortunately someone has to be the guinea pig. One more thing, just because one person in location X may find that Brand Y oil with weight 0W600 works perfect for them in their driving habits doesn't necessarily mean it will for someone else somewhere else with very different driving habits. That's my biggest concern with this. It's that one person will learn something, post it based on their specific results, and then everyone will arbitrarily copy it with nothing else to verify it works for them. Be careful to avoid this.
Also notice that rotaries typically run higher oil pressures than most piston engines. As he notes, a pressure increase is generally a flow increase. While this wouldn't be true with a centrifugal pump, the oil pumps are constant displacement driven off of a chain from the crank so in a perfect world this would hold true. As he notes, we also have oil pressure bypass valves. It has been set at different levels over the rotary years. It comes down to a rotary needing more oil flow through the engine. This is due to the necessary cooling of the rotors from the oil.
We also have the same needs as a piston engine in terms of bearing lubrication. The amount of lubrication needed on a bearing isn't as much as people think it is. Jeff (MM) found and has preached about restrictor pills in turbo oil lines and has noted that it really takes very little total flow to keep them happy. All that matters is that there is sufficient oil flow to keep the bearings lubricated. As the author pointed out, if you run higher oil pressures, you are just wasting horsepower. He never said that you'd damage your bearings. He did say that you would from a lack of flow though. This is where the balancing act of viscosity comes into play.
Keep in mind our bearings receive plenty of oil flow although in a stock engine the flow between the front and rear bearings is not equal which has led some to use different bearings between them. We run excess pressures to increase cooling oil flow through the rotors, not to protect the bearings. We have additional concerns that a piston engine doesn't have.
Finally we have oil being sprayed into the intake to lubricate the apex seals. This is what is responsible for more Renesis failures than anything. It's not the viscosity of the oil itself. The RX-7's had more oil metering flow than the RX-8 does and it was more directed to the center of the apex seals. The 3rd gen RX-7s only had the 2 nozzles in the rotor housings. One in each, direct center. The earlier carbed cars had them dump into the intake manifold and the 2nd gen RX-7's had nozzles in the lower manifold and in the rotor housings. Apex seals were much better lubricated in the pre RX-8 cars and hence engine failures were lower.
The RX-8 introduced 2 metering jets per rotor housing for a total of 4. Up from the 2 in the 3rd gen RX-7 and equal to those previous. However all was not equal. They pointed outwards towards the corners of the apex seals and not at the center. The center receives very little lubrication. However the center of the apex seal is the hottest part as the bending moment of the seal is at it's greatest here and so are the forces holding it to the rotor housing. This area of the seal needs lots more lubrication yet isn't getting any. This causes higher wear on the housings and the seals in this area which leads to lower compression, mileage, and power. Since each engine is different, it also causes different cars to dyno different power levels and get differing mileage numbers from others. None of this has anything to do with oil viscosity.
Viscosity does come into play though. A thicker oil will flow slower which will be less flow per time through the oil metering system. This is less lubrication to the apex seals. Bad news. While the older rotaries did run thicker oil, they also had better oil metering systems that took that oil where it needed to go. It doesn't matter how good your oil is. If it can't get to where it's needed the most, it won't do any good. That's what's wrong with the RX-8's. That is, until the '09s came out. A 3rd metering jet was added to each rotor right where it was needed. In the center of the housing over the center of the apex seal. You'll find these cars will be more consistent with one another in power and economy than the pre '09 cars will. They should have longer engine life too. The best thing a pre '09 owner can do is premix! Then of course we get into a whole new world of issues but I'm not dealing with them here.
As you can see engine oil has a larger role in a rotary engine than it does in the average piston engine. We are harder on it. It goes through greater temperature extremes and is required to do several different things. Because of this, we also need to base our oil choices on more severe requirements. The downside is that we make more compromises as what is best for oil cooling is not necessarily the best for bearing lubrication. What is best for bearing lubrication may not be the best for oil metering. This is why I prefer the Sohn adapter. It takes one thing out of the equation and allows you to run the best oil for metering while leaving the best for the rest of the engine.
Hopefully what I've just explained can help shed some light on reliability issues of the Renesis vs earlier rotary engines. It's not the oil! It's the oil metering system! I am not going to comment definitively on the weight issue though as there have been some signs that a thinner oil does lead to excessive bearing wear while a thicker oil doesn't. However there are also those that haven't found that to be the case. I think only time and more testing is needed in this area and unfortunately someone has to be the guinea pig. One more thing, just because one person in location X may find that Brand Y oil with weight 0W600 works perfect for them in their driving habits doesn't necessarily mean it will for someone else somewhere else with very different driving habits. That's my biggest concern with this. It's that one person will learn something, post it based on their specific results, and then everyone will arbitrarily copy it with nothing else to verify it works for them. Be careful to avoid this.
07-21-2009, 01:23 PM
#52
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My 2 Cents
One major difference between Ferrari engines and the rotaries.
A 12 cylinder Ferrari engine has at least 153 things that need lots of oil at startup.
7 Main Bearings.
12 Rod Bearings.
12 Wrist Pins.
48 Valve Stems.
48 Cam Lobs.
12 Pistons.
14 Cam Bearings.
The rotary has 4.
2 Main Bearings.
2 Rotor Bearings.
The oil does not need to go far in a rotary. But cant get to the apex,corner and sides, that is what oil injection and/or premix is for.
One main problem with the RX8 engine is the Oil Cooling System.
This is the same problem the 3rd gen RX7 has also.
Why is this? Oil cooler placement! All other rotary’s have one big oil cooler under the main radiator where it gets air flow all the time from the fan on the motor.
The RX8 and RX7-3 have oil coolers out in the corners where there is VERY LITTLE AIR FLOW below 20 miles an hour. I have been running an oil temp gauge on my second motor and what I see is horrifying. I can be in stop and go traffic with outside temps anywhere from 37F to 105F and get the oil temp up to 237F. Keep in mind that if you are using the under the oil filter adaptor (like the RB blue block) you are seeing the oil temp returning from the oil coolers, so the oil temp inside the engine is most likely 10-30F higher. I have noticed that this engine makes a lot of heat at 10-20 mph (1500-3000 rpm range), more than all other rotary’s I have owned (5-RX2, 1-1st Gen RX7 and 2-2nd Gen RX7). I ran both 2nd gens to 240K miles with 20w-50.
The other MAIN problem as we all know is apex seal lubrication. And with all this heat it makes this problem worse. (Premix Premix Premix).
Just to let you know, when I inspected my first engine (pulled at 97K miles for poor starts and power loss) the apex seals were so worn they were skipping along the housings, the side seals were sticking in the groves near the corner seals, the corner seal springs were almost full of carbon. Two of the oil control seal o-rings had failed (in pieces).
And yes this motor saw 9K rpm its whole life. 9K rpm and poor oiling at the apex seals = short apex life. 9K rpm does nothing for removing carbon (the only thing it keeps clean is the exhaust ports) 7K is fine. This motor did not get premix and ran 5w-20. The main bearings on the stationary gears were into the copper.
The side housing wear from the rotor housing movement was like the turbo RX7-3, this is heat related. The side seal wear at the corners was horrible. Side housing wear from corners, sides and control rings was good. The rotor housings were coated black.(Oil cooking).
I believe that too much of the wrong type of oil is injected at the corners causing this carbon build up and not enough at the middle of the apex’s (Premix Premix Premix)
I have been using premix on the second motor and 20w-50 oil.
I will be installing a blower fan on the oil coolers.
A 12 cylinder Ferrari engine has at least 153 things that need lots of oil at startup.
7 Main Bearings.
12 Rod Bearings.
12 Wrist Pins.
48 Valve Stems.
48 Cam Lobs.
12 Pistons.
14 Cam Bearings.
The rotary has 4.
2 Main Bearings.
2 Rotor Bearings.
The oil does not need to go far in a rotary. But cant get to the apex,corner and sides, that is what oil injection and/or premix is for.
One main problem with the RX8 engine is the Oil Cooling System.
This is the same problem the 3rd gen RX7 has also.
Why is this? Oil cooler placement! All other rotary’s have one big oil cooler under the main radiator where it gets air flow all the time from the fan on the motor.
The RX8 and RX7-3 have oil coolers out in the corners where there is VERY LITTLE AIR FLOW below 20 miles an hour. I have been running an oil temp gauge on my second motor and what I see is horrifying. I can be in stop and go traffic with outside temps anywhere from 37F to 105F and get the oil temp up to 237F. Keep in mind that if you are using the under the oil filter adaptor (like the RB blue block) you are seeing the oil temp returning from the oil coolers, so the oil temp inside the engine is most likely 10-30F higher. I have noticed that this engine makes a lot of heat at 10-20 mph (1500-3000 rpm range), more than all other rotary’s I have owned (5-RX2, 1-1st Gen RX7 and 2-2nd Gen RX7). I ran both 2nd gens to 240K miles with 20w-50.
The other MAIN problem as we all know is apex seal lubrication. And with all this heat it makes this problem worse. (Premix Premix Premix).
Just to let you know, when I inspected my first engine (pulled at 97K miles for poor starts and power loss) the apex seals were so worn they were skipping along the housings, the side seals were sticking in the groves near the corner seals, the corner seal springs were almost full of carbon. Two of the oil control seal o-rings had failed (in pieces).
And yes this motor saw 9K rpm its whole life. 9K rpm and poor oiling at the apex seals = short apex life. 9K rpm does nothing for removing carbon (the only thing it keeps clean is the exhaust ports) 7K is fine. This motor did not get premix and ran 5w-20. The main bearings on the stationary gears were into the copper.
The side housing wear from the rotor housing movement was like the turbo RX7-3, this is heat related. The side seal wear at the corners was horrible. Side housing wear from corners, sides and control rings was good. The rotor housings were coated black.(Oil cooking).
I believe that too much of the wrong type of oil is injected at the corners causing this carbon build up and not enough at the middle of the apex’s (Premix Premix Premix)
I have been using premix on the second motor and 20w-50 oil.
I will be installing a blower fan on the oil coolers.
07-21-2009, 01:40 PM
#54
In conclusion from all the responses and article, I think 0w-40 and an OMP adapter will be in my future. I can only hope by the time I install the adapter around 25kish mileage that it won't be too late to save the seals.
Last edited by Vlaze; 07-21-2009 at 01:43 PM.
07-21-2009, 01:40 PM
#55
Registered
The 1st (not the beehive) and 2nd gen oil coolers sat in front of the radiator. Nearly up against them. They were also sealed off decently so no air could go around them. This was important because these cars had a mechanical fan to cool the engine. This fan was ducted nicely (as it should be) to pull air through the radiator. However it also pulled cooling air through the oil cooler. The 3rd gen RX-7 and the RX-8 don't get this benefit which is why you are seeing higher oil temps at lower speeds in these cars.
07-21-2009, 02:03 PM
#56
ok, how did 5W20 kill your engine? The fact is neither you nor Kevin actually opened up your engine to see what was wrong (as per Mazda's orders)...
https://www.rx8club.com/showpost.php...2&postcount=72
and again your trading a 10x wear penalty for a 20W50 oil for every frikkin cold start of your engine in hopes of a slight lessening of wear in extreme high temp racing applications?? Is your car a daily driver, or a 100% track machine?
https://www.rx8club.com/showpost.php...2&postcount=72
and again your trading a 10x wear penalty for a 20W50 oil for every frikkin cold start of your engine in hopes of a slight lessening of wear in extreme high temp racing applications?? Is your car a daily driver, or a 100% track machine?
I gotta repeat this again ----- No other country has issued an MSP16 recall like we did. and sure its nice that we have 100K miles warranty on our engine, no one else got it but ------------------- that simply means, they know they fucked up, the bad name is spreading (once again), they wanna save their Rotary image, so what is there left to do? Throw a "free warranty program" out to calm these people down. The most important thing to this whole 100K warranty is that ----------
MOST owners will NEVER be able to tell that if their engine is having problems. as long as it start, it runs, get them from point A to point B, thats all they cared. not everyone is as ******* as me who complains the engine randomly shut itself down at red light (VERY very random, sometimes once a month, twice a week, 3 times a day, etc)
Compression in the 6.x psi? doesnt matter. it works. butt dyno cant tell them anything.
Also, almost 1/2 the time, for older rotary rebuilds, their bearings are "reusable", yeah, it came from people "that use" 20w50 with 10x wear start up rate.
Mr. 13B-MSP ? oh no, Im seeing copper. nope. not usable.
me nor Kevin opened the engine yea, but I think i've seen enough pictures of "unusual" wear on the main bearings. I mean yeah the engine still works, but is it suppose to be like that? I dont think so. For the reference, we're using the very same bearing(minor difference)
The 1st (not the beehive) and 2nd gen oil coolers sat in front of the radiator. Nearly up against them. They were also sealed off decently so no air could go around them. This was important because these cars had a mechanical fan to cool the engine. This fan was ducted nicely (as it should be) to pull air through the radiator. However it also pulled cooling air through the oil cooler. The 3rd gen RX-7 and the RX-8 don't get this benefit which is why you are seeing higher oil temps at lower speeds in these cars.
) I clean it out a bit. its not so good looking, but its better for airflow/cooling that way. simple but effective. The Fan shroud thing is good too, bad thing about it is the holes to hold the shroud in place breaks easily.
Last edited by nycgps; 07-21-2009 at 02:18 PM.
07-21-2009, 03:28 PM
#60
this is all a good read, I like what rotory god had to say, the problem is our oil is asked to do too many different things. when a person goes extreme on one aspect they loose on another
I like to make a point I think is worth mentioning
"one thing a lot of people seems to forget is, fuel dilution. It affects the viscosity a lot."
mixed with
another is when you change your oil aren't you only changing 5/9ths at a time so when you add your new 5quortes, isn't the 3 courts severely contaminating the new oil?
to me that's like running dirty/bad/contaminated oil all the time.
I just change my oil, and well after two fill ups I check the oil level and it was nearly black....
when you compare the FC FD and the rx-8 should't we look at the diffences with these motors rather then just saying the FC work great with heavy oil?
it sounds like different OMP and rates, and different oil coolers.
on the premixing side of things longterm does this not negitivly affect your fuel pump and fuel injectors?
I like the idea of the sohn adaptor, but I still think why didn't mazda do this in the first place?
I have also heard that the full blown racing engines have the omp unhooked to they just premix, or do they have some kind of sohn adaptor too, what does the mazda race team do?
could the oil injector nozzles be modded to spray the center?
I like to make a point I think is worth mentioning
"one thing a lot of people seems to forget is, fuel dilution. It affects the viscosity a lot."
mixed with
another is when you change your oil aren't you only changing 5/9ths at a time so when you add your new 5quortes, isn't the 3 courts severely contaminating the new oil?
to me that's like running dirty/bad/contaminated oil all the time.
I just change my oil, and well after two fill ups I check the oil level and it was nearly black....
when you compare the FC FD and the rx-8 should't we look at the diffences with these motors rather then just saying the FC work great with heavy oil?
it sounds like different OMP and rates, and different oil coolers.
on the premixing side of things longterm does this not negitivly affect your fuel pump and fuel injectors?
I like the idea of the sohn adaptor, but I still think why didn't mazda do this in the first place?
I have also heard that the full blown racing engines have the omp unhooked to they just premix, or do they have some kind of sohn adaptor too, what does the mazda race team do?
could the oil injector nozzles be modded to spray the center?
07-21-2009, 03:42 PM
#61
Momentum Keeps Me Going
Everyone is so at odds about the best oil for an RX-8, and even the experts among us admit no one can (yet) 'prove' what oil brand/thickness/type is better. Cars are used differently, in different climates, and even RX-7s and 8 are thrown in the mix. Everyone must have mental (not metal!) fatique trying to justify "the answer" one would guess! .. beyond.. "Heh! I know that this is right...what I'm doing, etc. is best".
So I though a little light reading might break the monotony. Sometimes trying to understand others problems can let one stand back and take a breath, and provide some insight. For your enjoyment I present the current 370Z engine oil enigma. These people experience their unique set of problems w/the 370Z, but the result is the same for owners...no guaranteed solution, many varied opinions, and most arguing against what the mother ship recommends.
This 4-page long article (next page links at page bottom - pretty hard to see) is heavy into high-tech oil & engine tech. It attempts to justify the 'real' reasons for the dealer's wanting $300 for a 'special oil' change to keep the 370Z engine lubed best. And it's sure an interesting read for those oil obsessed crazies among us, nano particles, atomic ball bearings and all....
http://www.370z.com/MagazineArticles...The-Truth.aspx
Point being, you can see yet again, but on a completely different engine, just how amazingly difficult it is to take "common oil knowledge", "just any good oil" whether syn or dino, "pick a weight" based on things people believe they know and can comprehend... things we often discuss here, and combine that to "prove what is best", when the technical problems are rather far more complicated and likely only understood by those who created and designed the engine.
What particularly bothers me (in general) is that aside from an owners manual recommendation, manufacturers themselves never seem to back up their recommended oil choices with any facts, figures, tests, or even half technical justifications for their particular engines that have problems.
They leave it to the world at large to justify (like here this web article) or just anyone else to play arm-chair quarterback, trying to devine the truth where little absolute knowlegde exists.
So I though a little light reading might break the monotony. Sometimes trying to understand others problems can let one stand back and take a breath, and provide some insight. For your enjoyment I present the current 370Z engine oil enigma. These people experience their unique set of problems w/the 370Z, but the result is the same for owners...no guaranteed solution, many varied opinions, and most arguing against what the mother ship recommends.
This 4-page long article (next page links at page bottom - pretty hard to see) is heavy into high-tech oil & engine tech. It attempts to justify the 'real' reasons for the dealer's wanting $300 for a 'special oil' change to keep the 370Z engine lubed best. And it's sure an interesting read for those oil obsessed crazies among us, nano particles, atomic ball bearings and all....
http://www.370z.com/MagazineArticles...The-Truth.aspx
Point being, you can see yet again, but on a completely different engine, just how amazingly difficult it is to take "common oil knowledge", "just any good oil" whether syn or dino, "pick a weight" based on things people believe they know and can comprehend... things we often discuss here, and combine that to "prove what is best", when the technical problems are rather far more complicated and likely only understood by those who created and designed the engine.
What particularly bothers me (in general) is that aside from an owners manual recommendation, manufacturers themselves never seem to back up their recommended oil choices with any facts, figures, tests, or even half technical justifications for their particular engines that have problems.
They leave it to the world at large to justify (like here this web article) or just anyone else to play arm-chair quarterback, trying to devine the truth where little absolute knowlegde exists.
Last edited by Spin9k; 07-21-2009 at 03:53 PM.
07-21-2009, 03:45 PM
#62
Some of the people posting in this thread did not read all the info on the link .
After reading all this I'm pretty happy with what I decided to do a while back which was :
Reduce OMP rate by 1/2
Premix at 250:1 (might up that to 200:1)
Run synthetic in the crankcase (recently started using 5w40 but will switch to 0w30)
Additional to this I will do the following as a result of reading all this :
Get oil pressure and temperature guages and actually know what to do with the information they provide .....
Namely wait till oil temp reaches close to engine temp before getting on it and monitor oil pressure at high rpm to determine if i'm running the correct viscosity oil and if the oil has degraded .
After reading all this I'm pretty happy with what I decided to do a while back which was :
Reduce OMP rate by 1/2
Premix at 250:1 (might up that to 200:1)
Run synthetic in the crankcase (recently started using 5w40 but will switch to 0w30)
Additional to this I will do the following as a result of reading all this :
Get oil pressure and temperature guages and actually know what to do with the information they provide .....
Namely wait till oil temp reaches close to engine temp before getting on it and monitor oil pressure at high rpm to determine if i'm running the correct viscosity oil and if the oil has degraded .
07-21-2009, 04:15 PM
#63
Registered
My feeling is that the older FB and FC RX-7 rotaries living longer had absolutely nothing to do with oil viscosity and everything to do with oil metering and cooling.
07-21-2009, 05:00 PM
#64
Super Moderator
Ah No (Flashwing), I am saying you need a thicker oil for HEAT protection...that is outside air temperature heat.
So why does the rest of Mazda's World say 5W30.....NOT 5W20, OH that's right the 20 is different in the US because you are "special"
...CRAP.
How come almost ALL Racing Groups who actually RACE ROTARIES use a Higher THICKER grade of oil ???????, not a 0w20, 30, or 40, but a 15 or 20 W 40 or 50.
In the days when we would only use 20W50 oils in rotaries I would hardly EVER sell Rotor Bearings or Stationary gear bearings, and NEVER sold an eccentric shaft...in 15 years.
And I was my states top selling parts dealer.
It has only been SINCE these so called BETTER and "Modern" oils have we been seeing Bearing Wear....so what does that tell you.
And possibly "extended" service Intervals.
So why does the rest of Mazda's World say 5W30.....NOT 5W20, OH that's right the 20 is different in the US because you are "special"
...CRAP.How come almost ALL Racing Groups who actually RACE ROTARIES use a Higher THICKER grade of oil ???????, not a 0w20, 30, or 40, but a 15 or 20 W 40 or 50.
In the days when we would only use 20W50 oils in rotaries I would hardly EVER sell Rotor Bearings or Stationary gear bearings, and NEVER sold an eccentric shaft...in 15 years.
And I was my states top selling parts dealer.
It has only been SINCE these so called BETTER and "Modern" oils have we been seeing Bearing Wear....so what does that tell you.
And possibly "extended" service Intervals.
Last edited by ASH8; 07-21-2009 at 05:30 PM.
07-21-2009, 05:06 PM
#65
Super Moderator
In the end, I still believe you should chose a reasonable priced good quality Oil and change it more regularly...at half the mileage/time the Mazda Manual recommends, or at least 3 times a year.
07-21-2009, 05:13 PM
#67
SARX Legend
iTrader: (46)
Ah, I'm thinking along the same lines as Brettus. I have spent a gang of cash lately but I'm gonna go ahead and order the RB pod and guages tonight. I sure wish more oil came out during regular oil changes.
07-21-2009, 05:17 PM
#68
1) So why does the rest of Mazda's World say 5W30.....NOT 5W20, OH that's right the 20 is different in the US because you are "special".
2) How come almost ALL Racing Groups who actually RACE ROTARIES use a Higher THICKER grade of oil ???????, not a 0w20, 30, or 40, but a 15 or 20 W 40 or 50.
3) In the days when we would only use 20W50 oils in rotaries I would hardly EVER sell Rotor Bearings or Stationary gear bearings, and NEVER sold an eccentric shaft...in 15 years.
And I was the my states top selling parts dealer.
It has only been SINCE these so called BETTER and "Modern" oils have we been seeing Bearing Wear....so what does that tell you.
And possibly "extended" service Intervals.
2) How come almost ALL Racing Groups who actually RACE ROTARIES use a Higher THICKER grade of oil ???????, not a 0w20, 30, or 40, but a 15 or 20 W 40 or 50.
3) In the days when we would only use 20W50 oils in rotaries I would hardly EVER sell Rotor Bearings or Stationary gear bearings, and NEVER sold an eccentric shaft...in 15 years.
And I was the my states top selling parts dealer.
It has only been SINCE these so called BETTER and "Modern" oils have we been seeing Bearing Wear....so what does that tell you.
And possibly "extended" service Intervals.
2) What are their bearing clearances and oil pump operating pressures in those racing engines?
3) And with the handful of engines I have built, not one had bearing/gear issues either. BFD.
07-21-2009, 05:19 PM
#69
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07-21-2009, 05:27 PM
#70
Super Moderator
1) Probably draconian federal regulatory concerns in the United States. We are a Socialist/Fascist country, ya know.
2) What are their bearing clearances and oil pump operating pressures in those racing engines?
3) And with the handful of engines I have built, not one had bearing/gear issues either. BFD.
2) What are their bearing clearances and oil pump operating pressures in those racing engines?
3) And with the handful of engines I have built, not one had bearing/gear issues either. BFD.
For what it is worth, the 09's Oil Metering System.
I have only noticed this occurs in Winter (now here) but when you turn off your car you can hear the EMOP's releasing oil into chambers, for next start up.
I can't remember hearing this in hotter weather. 09 Service highlights mention this function.
Ash
07-21-2009, 05:29 PM
#72
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The biggest thing to take away from the various information posted here is oil choice is not going to be the same for everyone. Everyone lives in different climates and have somewhat different operating conditions for the motor.
In the case of race vs. street, we all have to be really honest with ourselves and understand we're not all the bad *** racers that we like to think we are. Most of us are street driven with some occasional spirited driving. In the instance of race cars they can get away using totally different viscosity oils because of two factors.
1. They rebuild their engines more times in a race season than you probably will over the lifetime ownership of your RX8.
2. They are pushing higher oil temperatures in situations where engine stresses are higher for longer periods of time.
Those of you who do track your vehicles in club racing or HPDE only experience 20 minute runs while race teams are looking at HOURS of operation. I under no circumstances will even attempt to give an opinion on race car needs when it comes to oiling because I have neither the knowledge or experience in that level of performance.
Fred did an excellent job summarizing the various oiling aspects, the challenges this car faces and the issues we have faced. I agree 100% that the majority of failures are the result of the OMP system design more than anything else. This is why I opted into install the AP and the sohn adapter when I did.
I can tell you that observing Phil's 8's engine rebuild by Charles Hill, Phil has used 5w-30 in his motor for the punishing 15,000+ miles that were on his supercharged motor. The bearings were in excellent shape. That also, mind you, is dealing with the Vegas heat. Anybody who knows Phil knows he demands 100000000% out of his vehicles. This wasn't a babied car.
Fred, the issue of foaming regarding the rotors...is that more of an oil cavitation issue?
Finally, addressing the issue of the oil system. It was mentioned that people quickly see their oil turning black even after an oil change. This is one reason why I don't suggest long change intervals because 99% of the people here don't drain their coolers every time they do an oil change. This means approx 3 quarts of oil is still in the system. This is the reason I prefer to do a 3,000 to 4,000 (max) change interval. There is always going to be dirty oil in the system.
The other real question I have is regarding clearances and the differences between the 13B and the RENESIS in this regard. If it's true that bearing or other clearances in the RENESIS are tighter than previous generation rotary engines then the older philosophy of using a high viscosity oil doesn't apply.
Again, the biggest aspect I hope everyone can take away is the need to evaluate honestly what kind of driving you really do. Most of us drive our RX8 the way it was envisioned by Mazda. I agree that every vehicle faces compromises in its production and design which is why there is an aftermarket community. However, I think the "old school" philosophies are once again being applied to this motor which is much different than people give it credit for.
BTW, didn't Haas say that Formula 1 Ferrari cars are using really thin oils like 10 weight or 15 weight oils? Those motors rev to 15,000 RPMs. I know we're not a race car but that has to count for something.
In the case of race vs. street, we all have to be really honest with ourselves and understand we're not all the bad *** racers that we like to think we are. Most of us are street driven with some occasional spirited driving. In the instance of race cars they can get away using totally different viscosity oils because of two factors.
1. They rebuild their engines more times in a race season than you probably will over the lifetime ownership of your RX8.
2. They are pushing higher oil temperatures in situations where engine stresses are higher for longer periods of time.
Those of you who do track your vehicles in club racing or HPDE only experience 20 minute runs while race teams are looking at HOURS of operation. I under no circumstances will even attempt to give an opinion on race car needs when it comes to oiling because I have neither the knowledge or experience in that level of performance.
Fred did an excellent job summarizing the various oiling aspects, the challenges this car faces and the issues we have faced. I agree 100% that the majority of failures are the result of the OMP system design more than anything else. This is why I opted into install the AP and the sohn adapter when I did.
I can tell you that observing Phil's 8's engine rebuild by Charles Hill, Phil has used 5w-30 in his motor for the punishing 15,000+ miles that were on his supercharged motor. The bearings were in excellent shape. That also, mind you, is dealing with the Vegas heat. Anybody who knows Phil knows he demands 100000000% out of his vehicles. This wasn't a babied car.
Fred, the issue of foaming regarding the rotors...is that more of an oil cavitation issue?
Finally, addressing the issue of the oil system. It was mentioned that people quickly see their oil turning black even after an oil change. This is one reason why I don't suggest long change intervals because 99% of the people here don't drain their coolers every time they do an oil change. This means approx 3 quarts of oil is still in the system. This is the reason I prefer to do a 3,000 to 4,000 (max) change interval. There is always going to be dirty oil in the system.
The other real question I have is regarding clearances and the differences between the 13B and the RENESIS in this regard. If it's true that bearing or other clearances in the RENESIS are tighter than previous generation rotary engines then the older philosophy of using a high viscosity oil doesn't apply.
Again, the biggest aspect I hope everyone can take away is the need to evaluate honestly what kind of driving you really do. Most of us drive our RX8 the way it was envisioned by Mazda. I agree that every vehicle faces compromises in its production and design which is why there is an aftermarket community. However, I think the "old school" philosophies are once again being applied to this motor which is much different than people give it credit for.
BTW, didn't Haas say that Formula 1 Ferrari cars are using really thin oils like 10 weight or 15 weight oils? Those motors rev to 15,000 RPMs. I know we're not a race car but that has to count for something.
07-21-2009, 05:30 PM
#73
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In regards to engine failure it tells me that Mazda screwed up when they designed the oil metering system on these modern cars but they used to get it right. Fortunately your car has the fix! As far as bearing wear goes, I haven't seen anything definitely (key word) different. I've seen many older rotaries with dead bearings.
07-21-2009, 05:33 PM
#75
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Firstly, they normally use straight weights and not mulitgrade oils because they don't care about start-up wear and straight weights have less additives to break down in heat. Secondly, all the top teams will break the bank trying to use the thinnest weight oils they can get away with for 200-500 miles because of parasitic power losses. Even super thin qualifying lap oils are out there for use in some series.