[ZX-10R]

Originally Posted by SFV1LE

BMW E46 M3 bearing failures had nothing to do with the 10w60 viscosity, it was the bearing design/spec.

It's really both - tight bearing tolerance and high viscosity oil don't mix, this isn't complicated.

BMW may have spec'd the thicker oil for the same reasons discussed here, although I still think it's a little crazy. Although dry sump is more expensive, it's a vastly superior solution compared to the "band aid" of high viscosity (which does more harm than good - plus the crazy high oil pressures which may contribute to early oil pump failures)

I had my M3 bearings replaced 2x under preventative factory recall work but they never had an issue prior to this work. If it was the oil they would have changed the spec, it is still 10w60 today and E46 M3 is one of the best performing "old" cars at the track.

It may be "performing" on track, but that doesn't mean there isn't excessive bearing wear occurring that entire time - you already said you had the bearings replaced twice, is this a case of don't believe your lying eyes?

If you get your bearings replaced with the new design as indicated by by BMW and run the 10w60, you're good to go for hard use.

Wrong - I know several M3 owners running 5W-30 on track and no reported bearing failures, that is the correct grade (or close to it) to use - BMW has their head up their ass

Our 15w50 is not too thick for the track, at 250 F+ temps I'm glad it's in there and wouldn't use anything else. Porsche is a different design, requiring a different oil.

It is too thick - it's a band aid. My brother worked in GMs Advanced Vehicle Engineering division for over 10 years and studied oil extensively, I think he would know. Most people know basically nothing about oil.

[SFV1LE]

Originally Posted by ZX-10R

It's really both - tight bearing tolerance and high viscosity oil don't mix, this isn't complicated.

It may be "performing" on track, but that doesn't mean there isn't excessive bearing wear occurring that entire time - you already said you had the bearings replaced twice, is this a case of don't believe your lying eyes?

I made it clear they were replaced for preventative factory recall measure required to maintain warranty (not due to a problem with my bearings) with redesigned bearings each time. BMW took awhile to figure out the proper design. With both replacements my bearings showed zero excessive wear.

You know several E46 M3 owners who run 5w30 oil on track and they determined, against the reco of some of the best auto engineers in the history of the industry, that 5w30 is better?

I'm not sure what to say about that. All the top E46 M3 track-rats here in So Cal run 10w60, and there are a lot of them. They're hammering these motors on 100 degree days, and some have over 100K miles. Like any car you will get some normal bearing wear over time, but if your motor stays strong over 100k under these conditions, and theirs have, it's performing and lasting as designed. None of these guys would or should use 5w30 under these conditions.

Originally Posted by ZX-10R

It is too thick - it's a band aid. My brother worked in GMs Advanced Vehicle Engineering division for over 10 years and studied oil extensively, I think he would know. Most people know basically nothing about oil.

GM Corvette race teams use M1 0w50 Race oil, is it too thick? Professing to be an oil expert who knows more than world class engineering and racing teams (BMW and GM) who built some of the best cars and motors in automotive history is not something I recommend. Bob is the Oil Guy forum is a better place for a never ending and pointless discussion like that.

[ZX-10R]

0W-50 is still thinner than 15W-50 (or worse yet 10W-60), it's a significant difference.

BMWs call to run 10W-60 with extremely tight bearing clearances in the M3 is off the rails insane, and I'm not the only one who thinks that...hope you are babying the heck out of the engine until it's completely up to temp (i.e. oil temp gauge). I would be running 0W-40. Modern synthetics are so good that viscosity loss isn't the problem it once was (assuming fuel dilution is in check, which can be a problem for boosted applications). You may want to get a used oil analysis for viscosity and wear metals

[SJFGTO]

Originally Posted by ZX-10R

0W-50 is still thinner than 15W-50 (or worse yet 10W-60), it's a significant difference.

BMWs call to run 10W-60 with extremely tight bearing clearances in the M3 is off the rails insane, and I'm not the only one who thinks that...hope you are babying the heck out of the engine until it's completely up to temp (i.e. oil temp gauge). I would be running 0W-40. Modern synthetics are so good that viscosity loss isn't the problem it once was (assuming fuel dilution is in check, which can be a problem for boosted applications). You may want to get a used oil analysis for viscosity and wear metals

^^^ Yes!^^^

[SFV1LE]

Originally Posted by ZX-10R

BMWs call to run 10W-60 with extremely tight bearing clearances in the M3 is off the rails insane, and I'm not the only one who thinks that...hope you are babying the heck out of the engine until it's completely up to temp (i.e. oil temp gauge). I would be running 0W-40. Modern synthetics are so good that viscosity loss isn't the problem it once was (assuming fuel dilution is in check, which can be a problem for boosted applications). You may want to get a used oil analysis for viscosity and wear metals

I don't have my 2002 M3 now I sold it in 2005, I have a ZLE. I never push any car until the oil temp is at 200 F, even my MDX. I always keep RPMs below 3500-4000 until I hit 200 F.

In my ZLE I almost exclusively run the awesome factory engineer required 15w50--without this, at oil temps in the 270 F+ range on track my pressure, viscosity and film strength would be too compromised for comfort running on a 100 degree day at Buttonwillow on Pirelli slicks. Peak pressure drops a lot with oil temps this high on track and in logs, more so with lower weight oils. I have observed the data firsthand repeatedly. And if my motor failed on track with anything but M1 15w50 in it, I would not be covered by warranty--full stop.

If I had a non 1LE I COULD run 0w40, but I wouldn't due to my preference for better pressure at high temps. If I modded my ZLE I'd be anxious about failures out of warranty and would be getting oil analysis, but the ZLE doesn't need any mods to lap a lot fast than I can currently pilot it. I have a full warranty and will sell the car before it expires, so no need to worry about oil analysis.

If you meant get oil analysis on my 2002 M3, that bad boy is long gone--I should have kept it.

[ZX-10R]

Originally Posted by SFV1LE

In my ZLE I almost exclusively run the awesome factory engineer required 15w50--without this, at oil temps in the 270 F+ range on track my pressure, viscosity and film strength would be too compromised

From the previous link (Al comments), 15W-50 is spec'd to mitigate "oil pan drawdown" because of the lateral acceleration of the ZLE, it's not because of "film strength". Most modern synthetics are fine well into the 300s (F) range, I know Kawasaki jet ski racers running 10W-40 in endurance events where oil temps average 320+ F for hours at wide open, completely pinned throttle, probably the most severe engine test there is - Mobil 1 claims adequate protection to 500 F

Peak pressure drops a lot with oil temps this high on track and in logs, more so with lower weight oils.

What oil pressure makes you uncomfortable? Just curious - is this your perception or an actual serious problem? How do you know?

I have observed the data firsthand repeatedly. And if my motor failed on track with anything but M1 15w50 in it, I would not be covered by warranty--full stop.

Again that's for the reason outlined above - note that factory fill on the dry sump Z28 LS7 was.....drumroll.....5W-30

Is there a connection between these thick oils and early pump failure? Who knows, but it's definitely more stress on the pump. One thing for sure, higher viscosity oil doesn't flow through close tolerance parts as well.

Note that Honda now specifies 0W-20 (!) in the high boost turbocharged Type R, which is a very high stress engine - maybe Honda doesn't know what they're doing? Or maybe BMW didn't....oil is not a static science