Inversely, of the Renesis rebuilds I have done the ONLY ones which had near-perfect bearings were those that used synthetic oil (specifically, RP 5W30). They were all boosted, btw.

 

And again, article after article kind of explains that the numbers on the bottles do not mean a whole lot. I would much rather have a good 5W20 over Autozone brand 10W40.

 

I will take that..

Next, you have to look at how often was the car serviced, how often was engine oil renewed, how often was the oil filter replaced?...

One would hope that if (like many club members) are renewing engine oil at half the recommended intervals Mazda suggests would still have oil in good "condition".

 

Take this, then.........

I did not look at any records but it seemed to me the larger issue was low OMP volumes as I suspected with my own rebuild a few years ago.

I am not sure I properly understood your last statment. Sorry.

 

Ok Charles...ready....

Now you are starting on MOP's!..(like me) another issue, I thought we were on about bearings...

I should have also said, much of the "bearing wear" seen may also be attributed to poor maintenance (engine oil changes) and or owner related maintenance, not topping off, low oil volumes..which then passes to the MOP.

 

take this :




not directed at anyone - just seems to fit into the flow of the conversation

 

We agree from different perspectives, is all.

I can only empirically address that which I have witnessed myself and with the rebuilds I have done all the apex seals were wasted while the rest of the engine (for the most part and except for housing damage which was expected) was fine.

I can offer up my own engine as an example of a poorly maintained and typically abused Renesis refusing to give up but that may still not typify the Renesis.

 

For the record, that is my favorite "emoticon" and I laugh whenever I see it..........

 

Ash, you might want to read that article again caused you missed a couple points. First off, 10w, 15w, or 20w doesn't have anything to do with the thickness of the oil when it's at operating temperature. It only has to do with the thickness of the oil when it's cold.

A 10w-30 and a 0w-30 have the EXACT same cSt at 212 degrees. The same for a 20w-50 and a 0w-50. Using a thicker oil at startup has no benefits based on the principle that higher viscosity = less flow.

IF you are going to use a 50 weight oil then a 0w-50 would be the best to make sure you get the maximum amount of flow at startup.

So you're going to base your feelings about oil weight based on how many bearings you sold?

That was 40 years ago! Oil has vastly improved since then. While all the oils of today are backwards compatible the point is that oil properties at the time the RX7 was in full swing are ancient technology at this point. The newest oil API standards are vastly superior in every single way.

You simply cannot take everything that applied to the RX7 and apply it to the RX8. The technology is similar but there are vast differences.

You are being rather vague here but I assume you mean that it's due to viscosity and not oil pressure. The problem is they share a relationship.

The bearings are supported by hydrodynamic lubrication in that a film of oil separates the metal surfaces and keeps them from touching. Here is where Haas makes the premise that flow, not surface contact, is what lubricates the surface and keeps metal apart.

If that premise is indeed true, then you would want the oil that flows the absolute best across all temperature ranges. This oil doesn't exist.

Maintaining a hydrodynamic lubrication system does require a viscus liquid so there is a minimum viscosity that will protect your motor. The problem is if you have oil that is too thick it increases the friction that occurs on the metal parts. That friction creates heat which causes the oil film to thin.

The advantage of a thinner oil in this case would be increases in flow, lower friction created as a result and cooler oil operation.

For the sake of safety I'd simply suggest that people use an 0w-30 or a 5w-30 that is a full synthetic (Group IV or Group V base oil).

 

^^ Thank you

I was afraid I'd have to yet, repeat that fact on the first number being only good for start up and not the operating weight. I think Ash didn't read the article at all or much the less knew how to read oil weight rating with that type of response....

 

In the case of people who are going longer change intervals then using the more exotic style synthetic oils would be best. Their additive packages are the only thing that wears out and their viscosity doesn't change much over time.

Poor maintenance on any vehicle will result in a failure. No differences with the Rotary.

This discussion has been mostly about bearing wear as the aspect of OMP injection is a totally different subject for me since I inject 2 cycle oil. The requirements for the motor are different than what is used in the crankcase.

I can start another 2 cycle oil discussion but there's much less data to go on and I can't crack open my motor every 10,000 mile to see how it's doing.

 

Nor would you know how!

 

Oh I can take it apart just fine. Just don't ask me how to put it back together!

 

The key in all this oil discussion is to KNOW what your typical oil operating temp is and to contrast that with your lowest cold-start temp. The sad fact is that few of us actually KNOW what the hot temp will likely be but we will usually know what the low temp will be (because we see it on the thermometer/weather report every day). Since, in this case, Mazda already KNOWS what the hot temp is but not the cold temp (necessarily) they issue suggestions in the owners manual is based on the cold temps as most people wouldn't know **** if the hot temps were discussed, anyway.

If you are a typical DD/street-driven car use a good oil and keep it full.
If you are an occasional tracker don't let your maintenance regimen get too lax.
If you are a REAL racer, get to KNOW your hot temps, select the viscosity you think you need, and change your oil before every race.

BTW, IMO, oil temps in the Renesis are not the super-serious and delicate issue some have made it out to be around here.

 

I was one of those people until I got to listen to a very informable person. I still use my regular oil 5w20 for my area in PA, haven't premixed yet, and have 89,000+ miles on it, and running strong (knock on wood).

With all these threads it starts to make people a little paranoid when it comes to there cars since you are trying to get the most out of your baby. There is a lot of great info in this thread so far compared to others I have read so far.

My decision with regards to my car is I will keep running what I do, until there is more data on all oil uses in the 8 in different area's of the country and world. I know quite a bit about my car, and am still learning on the 8, but I will never stop even when everything is already discussed.

Like I have said before I need more gauges so I know more about the operation of the 8, and so far all I have is my scangauge which is pretty good, but I haven't figure everything out with it yet.

One thing I do know is the engine is like the body to a certain extent, to thick of blood can cause problems, and to thin of blood and there are problems.

Sorry that I sound like a dumbass right now, had a few to drink.

 

When you are in stop and go traffic for a long time and see the oil temp go into the 247 range its very super-serious.
That and poor oiling to the apex's killed my engine at 97K miles.

BTW, That's return oil temp to the engine, that means oil temp inside is higher.

 

I have oil temp end pressure gauges.
I never get such high oil temps in stop and go traffic (Hi-Power 2 oil coolers, Mobil-1 0w-30), according to my gauge that situation is not a big deal for the engine and the oil (max 212F). Dr Haas wrote the same.
Don't you have a problem with your oil cooler's thermostat, or is your car modded?

 

Yeah, but to be honest that is a cooling issue and not an oiling issue. Haas addresses this head on with the notion that people believe they need to run a thicker oil because of the hot stop and go traffic.

If you are having cooling issues then they need to be addressed by upgrading your cooling system with larger oil coolers or a better flowing radiator.

 

I know my car at first had problems similar to that, and I change the coolant and still had a problem, until I change the thermostat. I was seeing coolant temps around 215-230 or a little higher, so I guess the oil was higher, but when I change the thermostat I noticed that the old one had one less coil compared to the new one, just my observation from what I went through.

Now I am running coolant temps around 179-183*f consistantly, except stop and go which come to around 207-209 then the fans kick on and drop it down to around 190. Sorry I don't have the oil temp readings, but hope this helps a little.

 

Please don't forget that Mazda outside of the USA and Europe recommends engine oils ranging from 5W30's,10W40, 15W40, 20W50 for their RENESIS.

The "comparison" between the FC RX-7 and RENESIS of today is they USE the same Genuine Mazda Parts and Part Numbers for the OIL Pump Rotors, and Shaft, and the same Oil Pressure Regulator, all from 20 years ago, back then the oil recommendation (here) was 20W50 and we Mazda Dealers and Parts were not seeing the Bearing failures seen in Many RENESIS pulled down in the US, and shown on this club site.

You simply cannot take everything that applied to the RX-7 and apply it to the RX-8
I can in regard to what I have mentioned about, the rest of oil delivery through the eccentric shaft galleries and stationary gears is also the same. You tell me what is left that is not the same, apart from Oil Coolers.

This discussion has been mostly about bearing wear as the aspect of OMP injection is a totally different subject for me since I inject 2 cycle oil. I trust you are not suggesting there is any correlation to bearing wear and the MOP and it's function...

Yes, I agree that OIL Temps are also an issue with any rotary of today and past.
As we know the RX-8's needs more air flow through coolers.

 

BTW...

I would have to search to find it but I recall Paul from Mazmart saying his "main man" who does all his rebuilds including more RENESIS's than anyone else on this forum (this "old" guy with a little experience...appologies mate as I don't know your name ) suggestion to preferably use a 20W50 engine oil.

 

20 years ago, oil technology was such that 0w-20's didn't even exist, never mind the huge advances in oil and materials technology - to give yo an idea of the sort of leaps and bounds we are talking here, there has been as much advancement in materials performance over the past 10 years as there had been in the previous 200.

I'd take even a 0w-15 ester synthetic over some cheap wholesale mineral 20w-50 any day of the week

 

technology does improve over time, but there are things that simply never change.

what I mean is, people keep talking about "cold start up" and "use the lowest oil" possible, but seriously, at lets say 60f, it takes how many seconds to pump 20 oil, and how long to pump a 5w oil ? I would say the difference is very little. but on the other hand, 20w will have a "much stronger film strength" from start while the 5w ... will be kinda thin, it pumps fast, yes, but imo it is does not make it that much better.

not to mention, 20w oil will "stick" to your metal parts much better than those 5w oil overnight, so when you start your car the next morning, you will have more oil on your engine parts than 5w oil.

We see stupid engine wear starting Renesis, wear not suppose to be there until 100K+ miles. same bearings as the older gen.

Just my 0.02 ...

 

I did, in fact, just yesterday (before my car got pwned at night )

it was 85" outside, stuck in traffic, stop & go maybe like 5-10 mph.

then I see my water temp starts shooting up to 105 Celsius, and oil temp to a whooping 110 ~~~

Fan kicks on at highspeed, water starts going back down to around 90-94, oil to around 85.

if Im using 5w20 ... I dont know man ... its probably like water inside my engine ...

 

My additional two cents;

Stop-and-go traffic for a long time is not the paradigm upon which any car is designed (although the OEMs do try to over-engineer the cooling systems so as to accomodate it). Perhaps you have a rather unique and isolated situation you are dealing with.

Most of the suspected OMP-related apex seal failures I have seen happened long before 97K miles. You may have gotten lucky with your particular engine.

My point with the statement you highlighted was that we all seem to enter into a mild form of hysteria, buy all kinds of parts we may not need, and feel better for having done so without any proof that we (on an individual level) actually NEED the stuff we are buying. I made that same mistake when I swapped out my OEM clutch and that was how I discovered the "weak clutch pedal" situation.