Originally Posted by JCL (Post 945233)

Any DOT4 brake fluid from a name brand supplier that meets the spec. See your owner's manual. I think it is far more important to change it every two years than to try to upgrade the fluid spec. You aren't going to boil the fluid, so just go with the stock spec and rigidly adhere to the 24 month change cycle.

Engine oil is 5w-30, API SM or SN. Any name brand.

No engine oil additives. None. Why take a high performance motor oil and contaminate it with naptha, kerosene, etc? There is a reason that your owner's manual specifically recommends against all of them, they change the oil chemistry in uncontrolled ways. Bad news.

Oil filter should be OE (original equipment), from a dealer. You can take a chance on a will-fit filter with undocumented performance specs (including those filters made by OE suppliers) but why bother? Play it safe. New crush washer and filter seals at the same time.

Power steering fluid is Dexron unless labelled otherwise, some X5s were built using the Pentosin CHF-11s power steering fluid and are so labelled on the pump.

Differentials are 75w-90 from memory.

Transfer case is either Dexron (up to 2003) or BMW's secret sauce fluid from 2004 onwards. No aftermarket equivalent available. Get it from the dealer.

Coolant is another one you don't want to mix. Just use the OE fluid, flush it every 48 months.

I won't take a side here on the transmission fluid debate, there are enough threads on that one. Suffice it to say that there are two schools of thought; one says new fluid is better, so change it and damn the risk of flushing gunk through the transmission. The other says that transmission failures that have been seen aren't related to fluid failure, so save your money for a new trans eventually, as you will need one whether or not you pay $$ to change the fluid along the way. If you do change the fluid, and have done so every 30-40k, then it is low risk. Past that mileage interval, you run increasing risk of transmission failures post fluid change, even with the correct fluid correctly installed, and even if you had no transmission problems prior to the change. If you do decide to change it, use the correct ZF fluid (not a generic fluid), and use an OE transmission filter, as aftermarket filters have caused problems for a few people.

Jeff