Synthetic waste of money...my "opinion". I use 20/50 conventional and cars run fine.........one with 240 k and other 140K. Just change it frequently..thats the key. I do live in south so might, maybe, thin it out during winter if I lived in colder region. Work for oil company and had the pleasure of talking to scientists that formulate oil and they told me off the record that 0 weight oils aren't good for your bearings.....I know flame me but that's what I was told.
Callen 91 535i 94 530i 5spds