Use spec BMW LL01 and change every 25000km
1. Castrol has BMW suitable oils , contact SALUBE for distributor price 0116745391 ( e.g. Castrol TXT Softec Plus / Edge 5w40 ....etc)
2. Liqui Moly has good BMW spec oils .
3. Mobil 1 SAE 0W-40
Google for more and shop around