5W30 Oil Don't Cut it, Engine Bearing Pics 58K S1 RX-8 from England.
10-09-2009, 02:53 AM
#201
When we talk about doubled oil pressure we also have to remember that a good part of that increase is used to run\feed a double oil metering pump!
10-09-2009, 03:01 AM
#202
Ayrton Senna Forever
...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.
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.
Our problem is (in my opinion) as I wrote earlier that the oil bypass valve of the Renesis opens too early (even with lightweigt 20-30w oils) in the rpm range, so we can't increase the pressure and flow at higher rpm's.
The other is the e-shaft pellet, which keeps longer to get the oil to the bearings.
10-09-2009, 03:05 AM
#203
Ayrton Senna Forever
I'm sure that Mazda saw the lot of bearing wears on the replaced engines.
They had to step something to solve it. Did they change anything (related to the bearings) other than doubled the pressure? NO.
10-09-2009, 03:11 AM
#204
Agreed, but the fact is that we will never know for sure how much this pressure raise is bearing related or pump related 
Since cold start ups are not a problem for me because i have a garage i will stick with my 10w40 oil and call it a day.
Since cold start ups are not a problem for me because i have a garage i will stick with my 10w40 oil and call it a day.
10-09-2009, 03:40 AM
#205
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I agree.
Our problem is (in my opinion) as I wrote earlier that the oil bypass valve of the Renesis opens too early (even with lightweigt 20-30w oils) in the rpm range, so we can't increase the pressure and flow at higher rpm's.
The other is the e-shaft pellet, which keeps longer to get the oil to the bearings.
Our problem is (in my opinion) as I wrote earlier that the oil bypass valve of the Renesis opens too early (even with lightweigt 20-30w oils) in the rpm range, so we can't increase the pressure and flow at higher rpm's.
The other is the e-shaft pellet, which keeps longer to get the oil to the bearings.
10-09-2009, 03:42 AM
#206
10-09-2009, 04:13 AM
#207
Ayrton Senna Forever
...and you have got it already at 4000 rpm (even at the highest oil temp), and there are more 5000 rpms until the max 9000, but the oil flow won't be higher because you can't increase the pressure.....
10-09-2009, 04:24 AM
#208
Ayrton Senna Forever
Our mechanical MOP needs 0,5-1,5 Bar feeding pressure. Even it's pumping pressure not so high too. The new e-mops? I don't know, but I take 70/30 to bearing/e-mops on what was the causing factor for doubling the pressure.
10-09-2009, 07:55 AM
#209
Super Moderator
Thread Starter
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.
Paul.
Can you please ask Mr.E on the "suggestion" that over-tight Alt/Compressor Belts can cause a pressure point and mis-alignment of eccentric shaft, hence the Stat Gear Bearing Wear on the one location of the bearing tubes. In other words could over-tight Belts cause this bearing wear issue and not related to oil with the RX-8?
BTW: In the 100 or so Rotary Rebuild Engines I would supply genuine parts for in a year I would sell on average one to two sets of Stationary GEAR bearings if I was lucky per year, I only ever stocked 2 on the shelf #0820-10-502B, and two Rotor Bearings # 1011-11-111. They were not fast sellers.
Sold many Rotor Housings, Gasket Sets, Oil Control Rings, springs, o rings, apex and corner seals and springs, a few needle roller bearings for e-shaft, side seals and springs, and always a rear mail seal and timing cover seal...I have forgot anything?, 3 Irons were usually machined. Sometimes Oil Pump Rotors, always reused Oil Chains.
Rotors were always cleaned up and OK.
10-09-2009, 08:16 AM
#210
you know i asked Paul who also asked Mr E that same question. I was especially interested in this since i have added a s.c. belt onto the front pulley. Cam is not local so he wasnt available.
Bough Paul and through Paul -Mr E said they didnt think so.
I have seen this before with recips, but that point of wear is said to the the power pulse area of our engines so that is were it is showing up?
Maybe it is time for some bearing coatings--like the F1 guys use.
OD
Bough Paul and through Paul -Mr E said they didnt think so.
I have seen this before with recips, but that point of wear is said to the the power pulse area of our engines so that is were it is showing up?
Maybe it is time for some bearing coatings--like the F1 guys use.
OD
10-09-2009, 08:47 AM
#211
Wow, mine goes as high as 5 bars (72 psi), that's it. 7 bars? Do you own a SII version? IMO 7 bars sounds like overkill. I'm running 0w-30 atm but I can't see a weight change to 40 causing it to go up to 7 bars while it should be more than a 30 weight, but not that much.
10-09-2009, 08:48 AM
#212
you know i asked Paul who also asked Mr E that same question. I was especially interested in this since i have added a s.c. belt onto the front pulley. Cam is not local so he wasnt available.
Bough Paul and through Paul -Mr E said they didnt think so.
I have seen this before with recips, but that point of wear is said to the the power pulse area of our engines so that is were it is showing up?
Maybe it is time for some bearing coatings--like the F1 guys use.
OD
Bough Paul and through Paul -Mr E said they didnt think so.
I have seen this before with recips, but that point of wear is said to the the power pulse area of our engines so that is were it is showing up?
Maybe it is time for some bearing coatings--like the F1 guys use.
OD
No special coatings are needed. This is not rocket science, and as some of you may keep in mind; since we raced at practically the highest available levels for Mazda in the past we have used many very special coatings on rotors, flat housings, rotor housings, bearings. We've tried it all including high tech lower viscosity oils.
Paul.
10-09-2009, 08:52 AM
#214
Ayrton Senna Forever
As mine. The highest pressure is 5,1 Bar (74 PSI)
10-09-2009, 08:52 AM
#215
I would also say that my sensor is placed under the oil filter, the pressur may be slightly different from one point to another.
10-09-2009, 08:57 AM
#217
Mine is placed under the filter as well, since they don't have an oil adapter kit yet for the '09 (SII ~ Series II engines) for monitoring oil temp & pressure then I presume you have a series 1 ('04-'08) so I'm not sure why you're seeing that high of pressure. Idle I get the same pressure though, 1 bar ~ 14 psi. Strange. Not that I have a guide or chart to use as a baseline to say what one should be seeing as a max, just comparing to what people have reported here for highest pressure seen. I think you have the highest out of anyone I've read on here.
10-09-2009, 08:58 AM
#218
Ayrton Senna Forever
My sensor is at the same place as yours. Our measured 72-74 max PSI is same like the factory data.
10-09-2009, 09:02 AM
#220
Mine is placed under the filter as well, since they don't have an oil adapter kit yet for the '09 (SII ~ Series II engines) for monitoring oil temp & pressure then I presume you have a series 1 ('04-'08) so I'm not sure why you're seeing that high of pressure. Idle I get the same pressure though, 1 bar ~ 14 psi. Strange. Not that I have a guide or chart to use as a baseline to say what one should be seeing as a max, just comparing to what people have reported here for highest pressure seen. I think you have the highest out of anyone I've read on here.
Maybe i just slightly overfilled the system, considering what a rush my last oil change was!
10-09-2009, 09:08 AM
#222
Ayrton Senna Forever
The max oil pressure does not depend on viscosity and on overfilling. Otherwise I use 30w, (0w-30).
10-09-2009, 09:10 AM
#223
Oil pressure can change based on weights. Thicker oil will give more resistance and thus higher pressure readings. While it does give higher pressure reading, how much is questionable although I doubt anything over maybe 5 psi. We've discussed this in other threads.
10-09-2009, 09:15 AM
#224
Ayrton Senna Forever
The max pressure depends on your oil pump, and the bypass valve (valves), instead of the oil weight.
Maybe you can reach the max pressure ( 72-80PSI) even with water.
10-09-2009, 09:18 AM
#225
Wonder if my gauge is off-scale now...months ago i was seeing pressures of 6bar or so (a bit more than 80psi, so inside the gauge tolerance limits) I hate you guys, i will have to rewire it and see what's going on.