BMW E90 328xi Transfer Case Fluid Change

Although the transfer case fluid in modern all-wheel drive BMW's is considered to be "life time" it should be changed at least every 100K miles.  When the fluid gets old there will actually be a code stored in the control module letting you know that the life time of the fluid has been exhausted.  The code will not illuminate any lights on the dash and can only be read out using proper diagnostic software.  Once the error code is present the transfer case adaptation values will have be reset after the fluid change using the diagnostic software.  The fluid change described in this article was performed on a 2007 BMW 328xi.  On E90-E93 models the procedure is much more involved than it was on the previous E46 chassis.  In order to change the fluid the exhaust system and the heat-shields have to be completely removed.  To do this job right you will need to order one liter of Shell TF-0807 transfer case fluid, transfer case drain/fill plugs, two exhaust gaskets and four exhaust nuts.  You will also need a fluid pump similar to SL4344 pump we sell.

1.  Start out by removing the plastic under panel that covers up the transmission.

2.  Remove the cover that partially covers the transfer case.

3.  In order to remove the exhaust system the chassis reinforcement must be removed.

4.  Loosen the bolt for the exhaust bracket that holds the exhaust to the transfer case. 

5.  Unscrew the exhaust bracket from where it bolts up to the transfer case.

6.  Remove the 4 exhaust nuts and discard the nuts.  You might want to pre-soak the exhaust nuts in penetrating fluid if they look rusty.

7.  Remove the exhaust system.  I am missing a few pictures where you have to unscrew the muffler mounts but it should be pretty straight forward.  Don't just lower the front section of the exhaust without dropping the muffler.  Exhaust tips will push up on the bumper cover and possibly crack the bumper cover or damage the paint.  Once the exhaust is removed, remove all of the heat shields so you can access the transfer case fill plug.  Be sure to loosen the fill plug prior to draining the fluid in case for whatever reason you can't it to come loose.

8.  Once the fill plug is loose remove the drain plug and drain the fluid.  Discard both the drain plug and the fill plug.  

9.  Once the old fluid is drained install a new drain plug and pump fresh fluid into the transfer case using a hand pump until the fluid starts to spill out of the fill hole.

11.  Install a new fill plug, reinstall the exhaust heat shields, reinstall the chassis reinforcement, reinstall the exhaust system using new exhaust gaskets and new exhaust nuts and reinstall all of the underpanels.