m42 oil weight

[808AWD325xi]

My dealer recommended 15w40. They advised against synthetic as it would most likely cause oil leaks that did not exist today with the thicker dino oil.

[DCColegrove]

20w50 is NOT recommended in an M42 (or any other DOHC BMW engine) it will starve the HVAs (lifters) 10w30 or 40 is fine for the M42 (latter DOHC engines require 5w30).

I strongly recommend synthetic

15w50 is also fine however in cold weather it will also starve the HVAs)

[johnwoo]

cool thnks.

[dtdub]

I just filled up with Mobile1 full synthetic 15w50. I'd tend to trust the info in the Bentley, but realistically, there's probably no noticeable difference between 15w and 20w.

[johnwoo]

i know this has been asked, but i just wanted to confirm. the bentley says to use 15w50 oil but i read in some post that the m42 prefer 20w50, any confirmations on that? just wanted to know before i go and buy 5 quarts of the wrong weight, thanks.