2011 M3, 5000 mi, 50% RL 5W-30, 50% RL 40W race

[SteveSRT8]

Originally Posted By: A_Harman

M3's are noted for eating their rod bearings when tracked hard, so BMW decided to crutch it with thick oil.



Horribly, sadly, regrettably... TRUE!

Disregard their advice if you have the coin for a rebuild! I can tell you we watch the UOA's on my buddy's car carefully...

 

[OVERKILL]

Originally Posted By: A_Harman
Originally Posted By: OVERKILL
Originally Posted By: martinq
I have a hard time imagining what deficiency exists in this application that would require a 5.2 HTHS. Did they cheap-out on the cooling system or just not bother reworking it properly?


That would be a question for BMW. But I wouldn't be so quick to disregard their recommendation, particularly when the car is intended to be tracked, which would have been included in BMW's testing and subsequent recommendation.

No different than Ford spec'ing 5w-50 for the GT500 or BOSS 302.


M3's are noted for eating their rod bearings when tracked hard, so BMW decided to crutch it with thick oil.


I thought it was the E46 M3 that primarily had the rod bearing issues?

This of course had the I6 in it.....

The E9x has the S65, which is a 4.0L V8.

 

[OVERKILL]

Originally Posted By: martinq
I'm not disregarding it, I just don't understand where it's coming from. My guess is it's cooling related as that's the first easy-fix you can do when your temps get out of control. These are fairly high power-density applications but nothing outrageous (100hp/liter-ish). I just don't see how it adds up.


Well, Ford fitted the BOSS 302 with an oil cooler (the M3 has an oil cooler too) and still bumped the oil grade up to 5w-50. My guess is that, when tracked HARD, they are seeing oil temperatures that are elevated high enough to warrant the use of the much heavier oil.

With BMW, I think its a combination of the above, mixed with the fact that TWS has been their Unicorn Urine of choice for what has got to be close to 20 years now. It's a product that BMW Motorsport is familiar with in respect to its performance and operating characteristics and has been used extensively by them in their race program cars. They know how it works. So even if this engine perhaps doesn't require something QUITE so heavy, they are still safe recommending it, and it is widely available at all BMW dealerships, so service under warranty is easy as well.

Deviating from that recommendation, given that known performance at that point is NOT guaranteed, is a gamble. If the car is under warranty, it certainly isn't something I'd be willing to do, no matter how many people on the Internet told me to run something else.

 

[Radiation_Joe]

Just got the last report back after 9k miles on this mixture. Note the variability in the Blackstone results. 9k miles retains more of a variety of additives compared to 5k miles. For the current cycle I've switched up to RL 10W-40 street from the 5W-30. I really don't think it is necessary, but we'll see what it looks like after a few track days.

Also note there isn't a trace of lead in any of the three samples. The Castrol results come back with high lead quite often.

 

[147_Grain]

Joe:

I noticed that the last two oil analysis' showed a lot of molybdenum in them - 678 and 785.

Was Mos2 or something similar to it added to as an anti-friction modifier?

Most of the reports I've seen that show a lot of moly in them have outstanding numbers all-around. Zinc levels helped as well.

 

[Radiation_Joe]

Redline puts a lot of Moly in their oil. I'm not running any additional additives. As long as my results continue to come back this good, I don't see any reason to run the sludge BMW recommends.

 

[CATERHAM]

Originally Posted By: A_Harman
A 50/50 mix of RL 5w30 and 40WT race should give an HTHS of ~4.3, which is probably what the TWS 10w60 shears to after a couple thousand miles. The 40WT would give a substantial boost in zddp content over the Redline street oils.

I would agree with that assessment.

I've experimented with RL race oil/street oil blends; their 10wt and 5W-20 in my case and still found it to be a light 30wt oil.
Anyway, I don't really see the point of blending in their race oils, their street oils already have plenty of moly and ZDDP and their race oil VIs are very low.

In future I'd suggest trying RL 0W-40 (lighter than what you're running now) and blend in say 25% RL 5W-50. This will give you a slightly higher HTHSV of 4.4cP but with a 194 VI meaning the oil will be much lighter on start-up to the 150 VI mix tyou're currently running.

I'd also suggest since you track the car to install an oil pressure gauge. This is the only way to accurately know where you're at in terms of actual operational viscosity.

 

[Leonardo629]

And here I thought I was crazy running M1 0W40 in my M3....who's ready to try some 0W20...for street driving of course.

 

[CATERHAM]

We had a member who ran the very light TGMO 0W-20 in the winter in his E46 M3. Oil pressure was 57-58 psi at elevated rev's IIRC.
He loved it. I suggested adding a quart of M1 0W-40 to raise the OP a bit.

If your oil temp's don't get above 95C you should be able to run any 0W/5W-30 in a M3 and still retain some viscosity reserve to deal with possible fuel dilution.

 

[buster]

Originally Posted By: OVERKILL
Originally Posted By: martinq
I have a hard time imagining what deficiency exists in this application that would require a 5.2 HTHS. Did they cheap-out on the cooling system or just not bother reworking it properly?


That would be a question for BMW. But I wouldn't be so quick to disregard their recommendation, particularly when the car is intended to be tracked, which would have been included in BMW's testing and subsequent recommendation.

No different than Ford spec'ing 5w-50 for the GT500 or BOSS 302.


Good point.

I believe RL is a favorite among the BMW crowd.

 

[CATERHAM]

Originally Posted By: OVERKILL
Originally Posted By: martinq
I have a hard time imagining what deficiency exists in this application that would require a 5.2 HTHS. Did they cheap-out on the cooling system or just not bother reworking it properly?


That would be a question for BMW. But I wouldn't be so quick to disregard their recommendation, particularly when the car is intended to be tracked, which would have been included in BMW's testing and subsequent recommendation.

No different than Ford spec'ing 5w-50 for the GT500 or BOSS 302.

It's not wise to disregard any company's oil viscosity recommendation but by understanding the reasons behind the recommendation one can often easily maintain the minimum recommended operational viscosity using a lighter oil grade if the way they operate their vehicle so allows.
The more information you can get the better and installing an OP gauge which among other things is an effective viscosity meter will help a lot in that regard.