BMW E9x (E90, E91, E92) 328i (xDrive) Transfer Case Fluid Flush
Here is a video tutorial for draining and refilling the transfer case fluid in your E9x (E90, E91, E92) 328i (xDrive). The process is probably similar if not the same for 335i and M3 cars. The process is simple, like draining any other fluid. The most difficult part is removing the transfer case bracket due to a large bolt that is blocked by the exhaust piping.
Link to my Transfer Case Fluid/Oil Service Reset video
• Foxwell NT510 Elite - Transfer Case Fluid/...
Torque specs:
Transfer case bracket (small bolts) - 14 ft/lbs
Large transfer case bracket bolt - 50 ft/lbs
Transfer case drain and fill plugs - 44 ft/lbs
Outside of an assortment of sockets (8mm, 10mm, 18mm and E10) you will need a fluid pump. Here are a few amazon associate links (As an Amazon Associate, I earn from qualifying purchases):
https://amzn.to/3FkwH5w
https://amzn.to/45FDeCA
Here are links to the transfer case fluid (should only need one bottle):
https://www.fcpeuro.com/products/bmw-...
https://www.fcpeuro.com/products/bmw-...