sometimes i use valvoline synpower 5w40 and sometimes i go to the dealer and buy bmw oil,i don't see any difference if it's full synthetic mobil,castrol they are all good for your car:thumbup:hi all, could someone please suggest which engine oil is best for my 2000 528i m-sport. petrol, 77k miles. I'm thinking mobil 1 5w40 or castrol 5w40?? anyone heard of fuchs or comma too??