I own a 05 BMW X3 and i have just changed the transfercase on it, i bought a used one for around $1000, not cheap for a used transfer from 2006...the transfer was drained for oil when i got it and i need to fill it up With the right kind of oil, i use Castrol on my cars but the shop i use cant find the oil i need in their list, and there is no way im buying original BMW oil, it cost`s $100. for 1 litre so the big question....what kind of oil do you guys use in the transfercase `? Merc and Porsche use the same oil as BMW in their 4x4 transfers