In my 94 540i. I ran M1 15w50 in it this summer but I'm thinking that maybe a 5w30, 10w30, 10w40 synthetic may be a better choice. 285hp V8. The manual states 20w50 dino oil year round here in PA but I think that's pretty thick for winter time. I've got some Amsoil 10w40 and 20w50 on hand.