So, for you XI owners out there...does the XI have TWO differentials, one up front and one in the back? I know it has one in the back and a transfer case upfront, but I see a front differential on real oem and am now confused. I want to drain and refill my wifes E90 325XI differential and transfer case, and am going through my research phase, and am more confused now then before I think.

 

don't have an xi so can't be sure about bmw's setup, but most awd systems have a transfer case at or near the tranny with a drive shaft connecting the transfer case to the front diff. so yes, there should be a front diff.

 

if the engine is in a normal rear wheel drive position(crankshaft line goes from front to rear of car), then there typically is a front differential for awd or 4wd.

if the engine is mounted in the typical front wheel drive fashion(crankshaft line goes from one side to the other), then the front cv shafts go directly in the trans usually.

bmw has a traditional rwd engine layout, so they have a front differential, which is integrated to the oil pan. the drive shaft for the passenger wheel goes through the oil pan.

 

Thanks guys. Turbo i found the same picture on real oem. Does this mean that I have to drain and refill the front diff just like the back, with 75W-90 or since its integrated with the oil pan does the transmission fluid flow in the front one? In other words, should I plan on draining and refilling one or two differentials with 75W-90 oil on this X drive car - in addition to the transfer case?????

Edit - I know the transfer case uses a special fluid different from all the other fluids and have a quart of it already sitting in my garage, OEM BMW transfer case oil. For the diff's I'll be using Red Line 75W-90.

 

the front diff has its own oil. it is separate from the engine oil.
if you look at the pic, check out the plugs with the #9. one is for fill, the other for draining.
i believe any synthetic 75w-90 oil should be fine.

 

Thanks. So on the XI's there are 2 diffs and each can be drained and refilled with the same 75W-90 synthetic oil. this is in addition to the transfer case.

Not sure why but I couldn't find anything on this either here or on the E90 forum, and under their XI sub-forum no less.

This forum rocks! Blows all the others right out of the water.

Thanks again.

 

call your dealer and double check the fluid for the front diff. on the E60 AWD's, the front diff is now supposed to be filled with the transfer case fluid. only the rear diff takes 75w-90 unless you have a "M" which take 75w-140

 

Hmmm, you caught that I was asking about my wife's E90 XI, a 2006? But interesting nonetheless. I will double check with the dealer. Thanks for the heads up!