I use Idemitsu.

But any 2 stroke with at least TCW2 is good.

 

good parts guys are like good mechanics---if you find one --stick with them. They have seen and spoke to many more people than we ever will--sometimes about the same problem ywe are having. And they are full of suggestions , usually have more factory support /info than anyone. A good mechanic DEPENDS on a good parts guy, just like they depend on a good machinist.
If the parts guy you are dealing with has some knowledge it is easy to tell right off and you usually end up in a conversation. One just turned me on to some 2000F degree ceramic lube for the brake pins etc that Honda uses---and it works! Now all the Ga club folks use it. He also just told me of a "special" that my brand of oil will be on a sale next month and I will be able to buy a entire years worth of oil change(filters and oil) for 1/2 price.
Love my parts guy---i take them donuts!
In the old days they used to be equal to the internet
Worka holic Ash---understand those days--I too have paid a "price". If you survive it does make you stronger-- right dude?

You know with the increased cooling i have and the fact that oil temps follow the coolant temps I wonder if a better oil thermostat would be of benefit? Takes me 2-3 miles to even get to oil temps of140F. I do keep a VERY light load on her until I get to at least 160F

Now Premix? Thats a whole different story and other threads have the discussion going on.
OD

 

The Renesis stationary gear bearings are seeing considerably more off-axis load because of the much higher RPMs. It has nothing to do with the oil.

 

apparently our rotors are balanced a bit worse than those in the previous models. Add the extra rpms, the lubricants etc and the picture should be pretty much complete imho.

 

^^That's what I'm trying to get across, the load and heat in the bearing are related to the square of the surface speed, in the same way that the load on the pistons and rods in normal engine see forces that are related to the square of the engine speed, so that 'small' jump in the maximum rpm is a huge jump in reality.
Even though you're not likely to be going to the redline often, chances are even in daily driving you'll be using more rpms on average than the earlier engines.

 

Maybe Paul from Mazmart can chime in if the engines pulled from A/T cars show the same wear as ones from the higher RPM MT?

 

Though this is true, that isn't what I'm getting at.

The eccentric shaft moves like a jump rope, which means there is angular motion at the ends where the bearings are. The higher the RPM, the more angle the bearings see.

 

I have read pretty much every thread on Oil / premix / etc...

Still I am confused as is many....

Heres the question... I live in the NE ... it is about winter time. Should I use 5w20? 5x30? 0w20? 0w30? etc...


I am most concerned over longevity of the engine.

 

having trouble unterstanding then how a crankshaft would not be also exposed to these angular forces you are speaking of ?
Totally understand the higher rpm thing--one reason I NEVER go over 8K myself.
OD

 

So is a crank, which is why you see dual-mass flywheels as well as harmonic dampers on most engines these days (and why bearings die quicker when you take 'em off...)

 

Yes.
But the dynamic range of a typical piston engine is much smaller, so it is easier to norm for the critical speed of the shaft.
Even though the eccentricity of the mass is lower in a planetary (rotary) motor than a reciprocating one, there is still a harmonic series for the crank that can't be eliminated by counterbalance.

 

And don't forget that the stresses & reaction forces are proportional to the square of the crank rotational velocity.

 

Just commenting, but one of my colleague drives a RX8 that just passed 100K. After inquiring on any major issues and what type of oil shes uses, her replies were: none - 5w20. Food for thought.

BTW, we both live in Oregon. So, the weather might not be as severe as other RX8 owners who live in more hotter or humid environment..

 

What year was the car?

 

2005

 

Let's also not forget that for the longest time (and still somewhat today) this board has told every single new owner to redline their RX8 daily to remove carbon buildup. Early on people who claimed they did this seemed to have longer engine life and not suffer from having to have their motor replaced.

While I think it's important to run the motor out I think the success of that method was more due to the fact that the OMP provides maximum oiling in that upper range. Doing that daily might have saved some engines that would have otherwise failed.

...that and belt slippage I bet.


I found out that a local Mazda guy uses 5w-20 Mobile1 in his 550whp Mustang Cobra that is a weekend drag racer. Yeah it's a piston motor but I was surprised by this as well.

My point with all of this is that there currently isn't any real factual basis for which we see bearing wear or even replacements. Even if a scientific test could be arranged and paid for there probably isn't a single street car that would be maintained in the same manner.

There are a few corrections I want to make as well:

Oil doesn't lose it's viscosity due to exposure to heat (in the manner which it's referred to). It loses it by shearing. This is the process where oil molecules are broken apart.

It was also mentioned here or in another thread that film strength is directly related to film thickness aka oil viscosity. This isn't true either. Since the bearings are supported via hydrodynamic lubrication the problem is this process is very hard to maintain. Changes in load, contaminants in the oil as well as various other factors mean that sooner or later the HDL is going to break down.

So WHEN it does, there needs to be boundary layer lubrication that can continue to protect the bearings or other moving parts. This is where additive packages come into play and where the major differences in mineral vs. synthetic occur.

The point that I have been trying to beat into all of you is that basing your oil choic on viscosity alone is the wrong way to buy oil. For the exact same reasons that you don't base your car choice on how much horsepower the engine produces.

Viscosity, base stock, and the additive package are all factors that have to be taken into account.

The process for all of this is very simple. You choose the oil which flows the best while providing the necessary protection the motor needs. This means having an oil that meets the minimum pressure requirements by Mazda, that is a good quality synthetic and then having it tested to see how long you can run it before changing it.

If you are running hotter oil temps under heavy load aka track racing then you need an oil which will maintain a viscosity that flows like water but still meets the pressure requirements.

At this point if anyone has any questions about oil and wants to contact me directly feel free to do so. There's nothing else I can say that will make this topic any more transparent.

 

This is the same wear we've ever seen in the same places we've ever seen and in autos as well. We're seeing it more often and at earlier mileages (By far) on RX8s than anything before. We do not see this in the racing rennies that we run thicker viscosity oil in. The old man here has seen more engine bearings (Piston and rotary) than 100 of us together will ever see.

Paul.

 

So that means its still oil

I just put some 15w50 mobil1 with 20w50 RP (Cuz I only got 2 qts of RP, gotta mix it with mobil1)

Feels so good ~~~

 

Excellent points, well stated. I agree with everything you state, which is why I choose RP.

The only "yes, but" I can think of is that it is possible that with 5w20 or 5w30, the bearing in question gets into boundary lubrication conditions more frequently than intended by Mazda originally, which would result in accelerated wear. It is conceivable that a w40 or w50 oil is needed in this part of the motor to substantially reduce the number of boundary lubrication events that occur over the life of the motor, particularly for a car that is driven hard (which you do address above).

After all, the minimum film thickness is directly (although not necessarily linearly) related to viscosity, correct?

 

The issue is that film thickness is mearly the amount of seperation between metal parts. Film strength is how well an oil can maintain that film before shearing occurs.

The strength of a film is dependant on factors other than viscosity.

 

I can't believe you guys started another oil mega-argument thread, take it to "Bob is the oil guy" for crying out loud

 

for those that need this:

Oil Film Thickness refers to the theoretical thickness of oil film separating the surfaces

Oil Film Strength refers more to the lubricating characteristics of lubricant when the oil film breaks. It includes the ability of additives and other components, to hold lubricity even in cases of shock loads and vibration, and boundary lubrication.

Boundary Lubrication is when the oil film thickness is smaller than the average roughness of both surfaces under friction. In this case the film strength based on additives will support the lubricity and can be considered much larger than the oil film.

all the stuff being discussed can be confusing.

yep team-- its getting to be a very slippery subject.
od

 

I tried but no one responds, post the same threads over and over.

 

Bearing failures and gear wear aren't due to 5W-30W oil. Engines have been running 5W-30W for 20 years now. The reason for heavier oil in piston engines is for the rings not the bearings, and ring technology hasn't needed thicker oil for a long time.

Cryo may help the gears, certainly won't hurt. Having them micropolished won't hurt either, it better then doubles the life of helicopter gears. Most of the time if you want a stronger gear just up the Chrome and Nickel content, and/or carburize them rather then induction hardening.

The pics that started this thread are interesting to say the least. The gouges are a compelling case for pre-mix if they are from oil starvation. As I recall one of the flashes increased the oil flow a bit, I don't know if that cured it, but I do know plenty of these old RX8 engines have passed 100,000 miles without incedence. Always makes me wonder about how they were treated. For example how often oil is changed, what kind of oil filter etc.

What concerns me about premix is coking underneath the apex seals. Probably not an issue, just wish I knew a little more about the long term effects.

 

-..and our e-shaft's temps are higher than a crankshaft's temp, so we need higher flow to reach the same protection if we use the same viscosity oil.
-------------------------------------------------------------------------------------------
- As we know Mazda almost doubled the allowed oil pressure in the S2 Renesis. So they almost doubled the flow with the same viscosity.

- I think we would have to increase the maximum oil pressure in the S1 Renesis, to solve the bearing wear problem.