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      05-08-2009, 02:54 PM   #44
carve's Avatar

Drives: 335i
Join Date: Feb 2009
Location: usa

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Originally Posted by markinva View Post
please tell me what this

has to do with this:
Originally Posted by markinva View Post
interesting. here's some internet forum speculation I've read on the audi forums. these engines only had 4.0 qt capacities, only used dino oil, and had no electric oil pump or cooling for the turbos after the engine gets shut off. All in stark contrast to the bmw setup (7 qts, oil cools turbo after shutdown (I think?), and speciific syn oil).
(I thought I lost my mind when this was moved to M3)

OK...our oil pumps aren't electric- only the water pumps.

7qt of syn is WAY preferable to 4qt of fossil oil for resisting coking and for making is last longer. Still, hot running, 100hp/l turbo engines are more demanding on the oil, but the interval appears (yes- I'm speculating) unchanged from BMW's normally aspirated engines. That doesn't make sense. We also have no information about longevity goals BMW intended. I imagine the majority of people buying BMWs brand new don't keep them beyond the low 100k range, and already expect big depreciation, so that is a likely factor (yes, I'm speculating)

I'd be much less concerned running a (non-M) normally aspirated engine on the recommend change interval than a turbo or M engine.

In fact, when Subaru started importing turbocharged cars again (2001?), I think they had like a 5-7.5k mile interval, even on synthetic. By 2005 they changed that to 3,750 for all turbo engines, even if driven under mild conditions. Previously that was the interval for "extreme conditions" drivnig. Now they define merely HAVING a turbo "extreme conditions". The interval was implemented retroactively to ALL turbo subies. Think about it...they reduced their interval from 2x as often as BMW to 3-4X as often!