10w60 BMW M-cars

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Why is that BMW specs 10w60 for all of thier M-cars? I've seen some v8s and v10s torn down that were ran on mobil 0w40, and 20w50, and bearings and other internals were in great shape. Do you think these engines have fuel dilution issues and maybe that's the reason?
 
I seem to remember the M cars that were using 5W30 in the early 2000s had a lot of noise that the 10W60 oil took care of. Plus BMW assumes M cars will be driven harder so using the 10W60 is a better choice. Just like how on my Track Pack Mustang Ford recommends 5W50 vs the 5W20 usually recommended for Coyote V8s.
 
Your track pack mustang is a very good track car, I had a hard time 2 weeks ago getting around a guy with your car....after our
session he showed me his car, and was shocked it was stock....that motor revs like crazy...
 
The 10w60 "saga" was due to a run of M-series vehicles (Not sure whether in the 3 or 5 series) that were produced with sub-standard rod bearings. So the oil was meant to help alleviate the issue, although I think some were still rebuilt or replaced.

If you search up some of the old UOA's on the stuff, you will find the oil, whilst good, did tend to shear down from a -60 into a -50 quite readily.
 
Originally Posted By: B320i
The 10w60 "saga" was due to a run of M-series vehicles (Not sure whether in the 3 or 5 series) that were produced with sub-standard rod bearings. So the oil was meant to help alleviate the issue, although I think some were still rebuilt or replaced.

Yes, Castrol TWS 10w-60 was introduced around when the rod bearing issues came to light. Maybe they rushed the oil into service to band-aid the bearing issue. But that can't be the only reason because BMW kept speccing that oil long after the problems were fixed. In the S62 -- one of the affected engines -- they saw fit to go back to LL-01 oils, many of which are xw-30...
 
Originally Posted By: FranklinJL
Why is that BMW specs 10w60 for all of thier M-cars? I've seen some v8s and v10s torn down that were ran on mobil 0w40, and 20w50, and bearings and other internals were in great shape. Do you think these engines have fuel dilution issues and maybe that's the reason?

AFAIK, all we really know is:

1. The high-RPM M engines (S54, S85, S65) are intended to survive regular max-output usage, even in hot climates.
2. With that usage, those engines can produce obscene oil temperatures (think 300º F).
3. At those temps, most thinner oils would start to cook off in a hurry. That's uncomfortably close to the flash points of most oils.
4. Castrol's 10w-60 has a LONG development history, including in racing.
5. BMW Motorsport and Castrol developed their engines and oil in parallel. Each one accounted for the other in its design.

Obviously, most people granny the [censored] out of their cars (i.e. don't drive them anywhere near max). They'd never reach the temps at which other oils would fail but TWS would succeed. If I had to guess, I'd say that's why so many S65s and S85s seem totally happy on thinner oils. In fact, I've seen it plausibly argued that the tight bearing clearances on S65s and S85s almost necessitate a thinner oil unless you're always running them balls-out.
 
Sounds about right. Common practice in this area on the US is to run 0w40 around town, then 20w5 or 10w60 on the track...and that's for perfomance cars I've seen, from WRXS to Ford GTs, to some old dude that show up with a F40 from time to time
 
because they don't know how to design bearings and used 10w60 as a band-aid.

Napa has Liqui Moly 10w60 at a fair price
smile.gif
 
My understanding of the issue and subsequent spec'ing of 10w-60 for the S62 specifically revolved around excessive oil consumption due to the use of low tension rings and the heavier oil worked to help mitigate that somewhat. The post 03/00 cars had updated rings and in most countries spec'd the BMW 5w-30 or an equivalent oil meeting LL-01, which was what the engine was spec'd for originally before the consumption issue became evident.
 
Originally Posted By: edyvw
Rod bearing issue in E46 based M..


And the S85. Oil doesn't help in those, just seems to be a fact of life.
 
This thread is BITOG in microcosm. Blind repetition of half-truths that don't stand up to scrutiny...

Again: BMW M continued speccing Castrol TWS for years AFTER the rod bearing problems were fixed. They might have fast-tracked the introduction of TWS to band-aid the E46 M3, but that doesn't mean the rod bearing issue was "the reason", nor does it do anything to explain why the S85 and S65 continued to use that oil.

As for why future M engines use rod bearings excessively, there are a lot of hypotheses, some better than others. But whatever the case, try finding an engine with similar hp/L and piston speeds that DOESN'T eat rod bearings when driven hard. Good luck.
 
Originally Posted By: d00df00d
This thread is BITOG in microcosm. Blind repetition of half-truths that don't stand up to scrutiny...

Again: BMW M continued speccing Castrol TWS for years AFTER the rod bearing problems were fixed. They might have fast-tracked the introduction of TWS to band-aid the E46 M3, but that doesn't mean the rod bearing issue was "the reason", nor does it do anything to explain why the S85 and S65 continued to use that oil.

As for why future M engines use rod bearings excessively, there are a lot of hypotheses, some better than others. But whatever the case, try finding an engine with similar hp/L and piston speeds that DOESN'T eat rod bearings when driven hard. Good luck.

You are right here. Yes, TWS was band aid, but it was probably kept so it provides additional protection. However, I thought that S65 was backtracked to LL-01?
 
Originally Posted By: d00df00d
This thread is BITOG in microcosm. Blind repetition of half-truths that don't stand up to scrutiny...

Again: BMW M continued speccing Castrol TWS for years AFTER the rod bearing problems were fixed. They might have fast-tracked the introduction of TWS to band-aid the E46 M3, but that doesn't mean the rod bearing issue was "the reason", nor does it do anything to explain why the S85 and S65 continued to use that oil.

As for why future M engines use rod bearings excessively, there are a lot of hypotheses, some better than others. But whatever the case, try finding an engine with similar hp/L and piston speeds that DOESN'T eat rod bearings when driven hard. Good luck.


Well said sir! I really don't understand some members fixation on lower viscosity oils. Like that is some certificate of better engineering. BMW E46 M engines are really little bit civilised racing engines, later M cars are just normal, day to day driving machines. M inline six shouldn't be looked through a "only 300 something horses" prism.
It's a relic from a different times.
 
Originally Posted By: chrisri
Originally Posted By: d00df00d
This thread is BITOG in microcosm. Blind repetition of half-truths that don't stand up to scrutiny...

Again: BMW M continued speccing Castrol TWS for years AFTER the rod bearing problems were fixed. They might have fast-tracked the introduction of TWS to band-aid the E46 M3, but that doesn't mean the rod bearing issue was "the reason", nor does it do anything to explain why the S85 and S65 continued to use that oil.

As for why future M engines use rod bearings excessively, there are a lot of hypotheses, some better than others. But whatever the case, try finding an engine with similar hp/L and piston speeds that DOESN'T eat rod bearings when driven hard. Good luck.


Well said sir! I really don't understand some members fixation on lower viscosity oils. Like that is some certificate of better engineering. BMW E46 M engines are really little bit civilised racing engines, later M cars are just normal, day to day driving machines. M inline six shouldn't be looked through a "only 300 something horses" prism.
It's a relic from a different times.

That is the problem I have when people compare Corvette with M3 or something like that.
Euro norms, CARB etc. killed naturally aspirated M engines. But even with turbo, even more so, it is important to use heavy oils. BMW still is trying to provide much higehr rpms then competition. I would not be surprised if we see next M3 with redline at 8K. B58 is closed deck engine which means that BMW designed new inline 6 with much higher pressures in mind then N55.
 
I agree Eddy, BMW is still special when it comes to engines ( well at least M cars). Similar disputes I always had (still do) with my dad. He never could figure out what was so special about my Arese 2.5 24v because his diesel was almost as fast.
 
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