CTRismybeater
Member
- Joined
- Apr 24, 2020
- Threads
- 0
- Messages
- 43
- Reaction score
- 20
- Location
- Colorado
- Vehicle(s)
- 2011 E90 M3 & 2019 FK8 CTR
You’d be surprised actually. Above freezing 10w60 will lubricate all the engine just as fast as 0w20 and 5w50 probably just as well down to 20F. The bearing clearances in the R and probably the SI are probably pretty tight, but as long as you aren’t operating at the extreme end of the MRV spec you’d be fine. That said I doubt anything above a 40wt is going to provide any value and will eat power for hydrodynamic drag. I agree that fuel dilution is less an issue than most here think it is.I believe this is the case. Unfortunately, oil dilution is not the only concern and there are other places in the engine where 50 or 60 weight oil might not flow fast enough such as around the turbo and even more importantly in the valve mechanisms.
So I trest 30 as totally fine, 40 probably ok for more extreme (or hotter) driving, but I wouldn't go any higher just to prevent oil dilution.
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