The longitudinally installed BMW Z4 drivetrain came with a choice of three styles of transmission:
- 5-Speed Manual transmission with manual clutch.
- 6-Speed Manual transmission with manual clutch.
Automatic Steptronic transmission with choice of Normal, Sport or Manual mode. When Manual mode is engaged, the driver can upshift or downshift through gear ranges by flipping the shift lever forward or backward.
The manual transmissions are filled with manual transmission fluid while the automatic is filled with ATF (automatic transmission fluid). BMW specifies "lifetime" fluid for all its transmissions and sometimes defines lifetime as 100,000 miles. I think it is a good idea to service your fluid every 60,000 miles. If you're unsure of the last service, replace the fluid as soon as possible. Doing so will extend the life of your transmission.
If you're unsure of the last service, replace the fluid as soon as possible as it helps to take preventative steps to avoid future issues. Also, maintaining the transmission with fresh fluid will extend the life of your gearbox.
There are many options for replacement fluid. A good rule of thumb is, choose the best you can afford and be sure it meets BMW's current specifications for your vehicle.
Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.
Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.
Vehicle models change and evolve as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.
The following are steps highlighting replacing the transmission fluid in a BMWZ4M with a manual gearbox.
Drive your vehicle for about five minutes to warm the transmission fluid. Jack up all four corners of your vehicle. I suggest using four jack stands and slowly raising vehicle to the required height. The vehicle needs to be level when checking and replacing the fluid. Next remove the splash shield. See our Pelican Parts Technical Article on Removing the Engine Splash Shield and Reinforcement Plate.
The manual transmissions are filled with manual transmission fluid (inset) while the automatic is filled with ATF (automatic transmission fluid). Z4M models take MTF-LT-2 fluid. The fill (red arrow) and drain (purple arrow) are visible from below. Make sure you use the correct transmission fluid as they are not interchangeable!
Working at the side of the transmission, remove the 8mm Allen fill plug (red arrow). The fill plug can be tough to get out at times. If this is the case, use a3/8" drive ratchet with an 8mm Allen socket, this will provide enough leverage to remove plug. The sealing O-ring is part of the plug (purple arrow), I suggest replacing the fill and drain plugs.
Place the drain pan (purple arrow) under the transmission and remove the fluid drain plug (red arrow). Be sure your drain pan has a capacity of at least four liters. Once fluid has drained, reinstall and tighten the drain plug.
Using a fluid pump (purple arrow), fill the transmission until fluid flows out of fill plug hole (red arrow). Then allow it to run out until it flows out slowly from bottom of hole. Install the fill plug and tighten.