Rear Diff & Transfer Case Fluid Change Today

[USAF M6]

2011 35d, 100K miles.

Very easy to do the transfer case and rear differential fluid change. Had to cut a 1" piece of 14mm allen wrench to fit between the transfer case drain plug & transmission crossmember. Both TC plugs and the single diff plug used a 14mm allen wrench. Then I replaced the transfer case & rear diff plugs with magnetic plugs. There is no drain plug on the rear diff and you'll need to use a means to suck that dry. I used a tube on a big syringe and it worked great.

First pic is of the difference between the magnetic and original drain plugs. No clearance issues even though the magnetic ones are longer.

2nd pic is of the location of the fill plug on the transfer case on the drivers side. I have the 14mm allen socket in the fill plug. The fill plug is facing the front of the car up higher & the drain plug is facing the rear near the bottom. Both towards the drivers side of the TC.

3rd pic is of the 14mm allen wrench piece I cut to fit so I could remove the drain plug in the TC. Replaced that plug with a magnetic one so now it can be removed with a box-end wrench.

4th pic is of the fluid bottles. For both the real diff & TC, just when the pump started to spit air when pumping, they were full so they both used about 95% of the liter.

Easy to do and recommend doing this. Do it yourself and get the added satisfaction of ownership by working on your own car vs. paying someone to do it.

[Poppyboy]

Thanks for sharing! I just found out about there no longer being a drain plug. BMW's insane about preventing DIY'ers. I'm shocked at how much it costs to change the transmission fluid. I was quoted $535 by my Indy to do only the fluid, and another $400 for the pan/filter. Apparently, the trans fluid is crazy expensive.

[mitch808]

Originally Posted by Poppyboy

Thanks for sharing! I just found out about there no longer being a drain plug. BMW's insane about preventing DIY'ers. I'm shocked at how much it costs to change the transmission fluid. I was quoted $535 by my Indy to do only the fluid, and another $400 for the pan/filter. Apparently, the trans fluid is crazy expensive.

Insane? Or protecting dealer revenue and BMW OE parts sales?

[Poppyboy]

Originally Posted by mitch808

Insane? Or protecting dealer revenue and BMW OE parts sales?

Obviously. However, OE parts are commonly used by DIY'ers, evidenced by this post.

[007_e350]

Originally Posted by USAF M6

2011 35d, 100K miles.

Very easy to do the transfer case and rear differential fluid change. Had to cut a 1" piece of 14mm allen wrench to fit between the transfer case drain plug & transmission crossmember. Both TC plugs and the single diff plug used a 14mm allen wrench. Then I replaced the transfer case & rear diff plugs with magnetic plugs. There is no drain plug on the rear diff and you'll need to use a means to suck that dry. I used a tube on a big syringe and it worked great.

First pic is of the difference between the magnetic and original drain plugs. No clearance issues even though the magnetic ones are longer.

2nd pic is of the location of the fill plug on the transfer case on the drivers side. I have the 14mm allen socket in the fill plug. The fill plug is facing the front of the car up higher & the drain plug is facing the rear near the bottom. Both towards the drivers side of the TC.

3rd pic is of the 14mm allen wrench piece I cut to fit so I could remove the drain plug in the TC. Replaced that plug with a magnetic one so now it can be removed with a box-end wrench.

4th pic is of the fluid bottles. For both the real diff & TC, just when the pump started to spit air when pumping, they were full so they both used about 95% of the liter.

Easy to do and recommend doing this. Do it yourself and get the added satisfaction of ownership by working on your own car vs. paying someone to do it.

v nice op, was the fluid bad ... also will you attempt trans ? I plan on doing all three, some day

[USAF M6]

All the fluids appeared better than I thought they would with 100K miles.

I changed the trans fluid and engine oil the day before. I'll post that now...

[mweisdorfer]

Assenmacher makes a 14mm snub socket that works for the transfer case. It runs about $19-20.00. Bav auto also sells a 3 piece kit for various sizes in snub sockets too.

[therealm3]

Did the transfer case only use 1L? i am getting set to do all fluids on our X5 and want to know how much to order. Thanks!

[randrews15]

Just some added things since I just did this service. The front diff requires the removal of the front left wheel to access the fill hole. It was a pain to put the plug back in due to a transmission line in the way that at least was flexible. Now, the transfer case required the removal of the skirt to the left of the case for easier access to the fill plug. Once I did this I had no problem using my 14mm Allen socket. Interesting is that there wasn't a drain plug on my case. I don't know if it's because I have a newer 2013 X5 that was made without one. I used my Motive fluid extractor to suck out what fluid I could and filled it back up. Each diff and transfer case took less than a liter of fluid. Not a bad job, but very labor intensive as it requires more steps that posted here. The old fluid was brown and nasty for 52k miles, as compared to the new fluid that was bright yellow and clear. Glad that I did it to make the family truckster last longer.