What oil for X3 Transfer case and diffs?

Originally Posted by hottuna

i havent purchased the 14mm allen key as yet. Im planning on taking it to my mechanic soon once he`s back from the states racing top fuellers and im sure he has one

Im getting everything i need so i can drop it off with the car. He suggested we flush all the oil in the transmision including lines and cooler as he doesnt like the idea of just draining it and topping up - something out doing half a job.He is fussy which is good I know this will use about 18ltrs of oil.

Sounds like it will be more than $50 USD lol

Ok I just hid 100K Miles a week or so ago, and the car must have noticed, since it needed everything done. I did a cooling overhaul and oil filter gasket replace, but the dealer also recommended changing the trans fluid and diff fluids, like on this forum.

I went underneath to look at the trans case though, and there's a nice sticker under there that says something to the effect of "DO NOT OPEN THIS, DUMMY! Transmission oil shouldn't be changed for life!" So, now I'm quite puzzled. Is this just an American thing? Do I really need to change the oil out?

Bear with me if this is a dumb question, I'm just getting used to the DIY stuff.

BMW says the fluid is "lifetime"] but we all know that's not true

Right, so what's a good recommended interval, 100K? Is it worth going through and truly flushing, or is draining and doing a filter replace enough?

Originally Posted by avoisin

Right, so what's a good recommended interval, 100K? Is it worth going through and truly flushing, or is draining and doing a filter replace enough?

I am sure you will get many different opinions. Personally, I think it depends on your driving environment (city vs highway). More steady state driving, longer distances - change after more miles. I think starting and stopping creates more heat and stress to the fluids.

I changed diffs and transfer case around 70k, trans at 100k. Looked right for me on my X3.

Flushing is the best for the trans. I just did a drain, wipe pan and change filter.