[nomile]

1) Obtain special fluid from BMW - it's about $50-60 per liter, but you only need about 0.5-0.6L. While you are there, get a new "drain" plug. I reused the "fill" plug b/c I only had one spare.
2) Cut 25-30mm off a 14mm allen key. Clearance is tight, so the short piece makes it doable.
3) Jack up car, with the rear slightly higher than the from (drains fluid better)
4) Identify "drain" and "fill" ports - loosen the "fill" plug FIRST to make sure you can get the 14mm in there. It's a tight fit, but with enough fiddling, can be done. I used the open end of the wrench - experiment a bit.
5) I partially unscrew the "drain" plug to control the flow of oil a bit. Makes less of a mess. See images.
6) Used a cheapo pump to refill the transfer case

Notes:
- I have done this on an early-2007 and a late-2007 (pre-TPMS sensor and post-TPMS sensor). The late-2007 car went into a form of limp-mode (4x4-light, I think) after I did this procedure until I reset one of the transfer case sensors with the BT tool. The early-2007 car did not complain - possibly fewer sensors? Not certain.
- Do this earlier than I did - as you can see the oil was heavily discolored and cloudy. About 85kmiles. Did the other car at ~65k, and the oil looked better (whatever that is worth)

Good luck!

[tubesguy]

Thanks! Nice to have some pics to visualize what others have described.

[Wayne's World]

I took a chance and used this:
http://www.amsoil.com/StoreFront/ima..._qt_640pxh.jpg

Been using it for 6 months now and no issues. 75w, GL4. At $15/qt, it's decent stuff.

[Ph0zenstone]

Thanks for the DIY!

Old fluid


New fluid

[ska///235i]

op, what u use to cut the allen key....a saw with metal cutting blade?

[kluski]

Thanks for the write up.

Instead of cutting and Allen key, I bought an Allen socket from Harbor Freight and punched the key portion out. It was a perfect length.

The process is straight forward, but just a PITA trying to get the key into the plug. I ended up trying to tape the key onto the wrench, which kinda worked, but then I could not remove the wrench to readjust it. So I ended up using two fingers from each hand and stretching around the brace near near the case to put the key in.

Then I used my foot to push hard enough to overcome the torque necessary to break the plug loose.

Oh, and I did not need to reset any codes for my 2006 330XI. Been driving for 50 miles now and no problems/codes/faults.

[Aznfe]

Originally Posted by kluski

Thanks for the write up.

Instead of cutting and Allen key, I bought an Allen socket from Harbor Freight and punched the key portion out. It was a perfect length.

The process is straight forward, but just a PITA trying to get the key into the plug. I ended up trying to tape the key onto the wrench, which kinda worked, but then I could not remove the wrench to readjust it. So I ended up using two fingers from each hand and stretching around the brace near near the case to put the key in.

Then I used my foot to push hard enough to overcome the torque necessary to break the plug loose.

Oh, and I did not need to reset any codes for my 2006 330XI. Been driving for 50 miles now and no problems/codes/faults.

How do you punch the key out of the socket???

[E36graduate]

I use Mobil 1 synthetic ATF. Did it around 90K and then when I did my clutch at 120K. When I took out the ATF at 120K (30k miles on ATF), it looked like new.

I'm not saying this is the way to go, but there is a lot of discussions out there about atf and the bmw oil engineered just for the TC.

Originally Posted by Wayne's World

I took a chance and used this:
http://www.amsoil.com/StoreFront/ima..._qt_640pxh.jpg

Been using it for 6 months now and no issues. 75w, GL4. At $15/qt, it's decent stuff.

[gray boy]

i cut the 14 mm, leaving just enough to get the (ratchet) wrench on it. And i bought a quality, (expensive ) wrench that allowed small movement and i had the
fill plug out in two minutes.
extremely easy compared to the tran drain and refill.

[dw1]

Question: Is there a significant reason to use the BMW bottled power diverter oil rather than a good 75W GL4 synthetic fluid from Mobil / Amsoil / Red Line? I do see that the BMW fluid is clear and most gear oils tend to be gold in color. Thanks.

[deeLow]

Originally Posted by dw1

Question: Is there a significant reason to use the BMW bottled power diverter oil rather than a good 75W GL4 synthetic fluid from Mobil / Amsoil / Red Line? I do see that the BMW fluid is clear and most gear oils tend to be gold in color. Thanks.

Uhhh, I'll pay you 100$ if you put gear oil in the transfer case and it doesn't blow up.

[dw1]

@deelow: can you provide some specific technical details on your post on the differences in the BMW oil & other 75W GL4 lubricants?

[deeLow]

@dw1

Not necessarily, but the cost difference between all the others and the OEM bmw is NOT enough for me to risk blowing the TC. I went with the bmw fluid strictly for this reason.

I'd hate to see you/anyone else on here smash the case because of a few dollars really.

[ska///235i]

I have a bottle of oem TC fluid and drain/fill plug (traded the car) if anyone os interested

[dw1]

I am very much so.

[ryancole]

Thanks for the DIY. I just did this along with my MT and both diffs on my 2007 335xi. The trick with the small hex bit worked like a charm and overall a fairly quick and easy job. Just a note that it only requires about .5 qt of oil so don't be surprised when it starts overflowing out the fill hole sooner than expected.

[ucdbiendog]

Originally Posted by ryancole

Thanks for the DIY. I just did this along with my MT and both diffs on my 2007 335xi. The trick with the small hex bit worked like a charm and overall a fairly quick and easy job. Just a note that it only requires about .5 qt of oil so don't be surprised when it starts overflowing out the fill hole sooner than expected.

just did the same on my '08. I ended up removing the cross brace under the xfer case to get access to the fill hole, sort of a pain to get it off, but i had no luck getting to the fill plug prior to that.

[dcaron9999]

What reset tool are you guys using to reset the TC after the fluid swap? Is this a necessity? Im about to do this to my 2009 328i xdrive and have about 600ml left of TF0870 BMW fluid. The fluid has been sitting around in a bottle for a couple of years, ever since I change fluid in my old X3. Thanks.

[dcaron9999]

Just did this on my 2009 328i xdrive with 142,000Kms. Ended up loosening the cross brace without removing it to access the fill hole. The large transverse bolt would not come out of the cross brace as the exhaust pipe was blocking it.Quitre cramped up there even with a loose brace that you can move out of the way a little bit.

Id like to add that after draining the old dirty fluid, I had extra fluid which I used to purge the transfer case of the old remains. Once clean fluid started draining out. I put a new drain bolt back on and tightened it. I proceeded with filling with fresh fluid and approximately 600ML went in before spilling through the fill hole.

Make sure you clean any oil stains from all areas that get hot, or you will be smelling the stuff for a while ...

[Greyfox]

Tag for reference...

[bvanderhaar]

Very simple - no need to remove any of the under body covers. Easy with these tools:
http://www.amazon.com/gp/product/B004W80PEW - punch out the hex key
http://www.amazon.com/gp/product/B0002NYD80 - use the ratcheting part for fill plug, use the other end for the drain plug. The ratcheting end is a little too big for the drain plug.

I replaced both the fill and drain plug. Old oil was very dark; new (from BMW dealer) was clear-ish. I swear closer to 650 ml went in, but it could be the extra from the pump line and drain from the over fill.

[Kunlune90]

changed transfer case fluid today for E90 2010 328i xdrive, 126687 miles. First time transfer case fluid change.

Let car sleep before drain the transfer case fluid. Put in OEM transfer case fluid.
Drained out about 350 mL fluid and put in about 500 mL. The fluid drained out is black but no burnt smell. The same smell as the new fluid. Maybe the long miles consumed some transfer case fluid, but there is no code and the car drives normal.

Driven 15 miles with no codes. Scanned with OBDII and no hidden codes. Seems setting not needed.