The longitudinally installed BMW E46 drivetrain came with a choice of three styles of transmission:
- Manual transmission with manual clutch.
- Sequential manual 6-speed gearbox (SMG) with automatic computer controlled hydraulically operated clutch. SMG models are equipped with paddle-shift levers on the steering wheel.
- 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 and SMG 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 are 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 you are 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. Do you have 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 BMW E46 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 the 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.
Working at side of the transmission, remove the fill plug (green arrow). The fill plug can be tough to get out at times. If this is the case, use a 1/2" drive ratchet with a 17mm socket - this will provide enough leverage to remove plug. If you have a hard time getting it out, I suggest replacing the fill and drain plugs.
Place the drain pan under the transmission and remove the fluid drain plug (green 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, fill the transmission until fluid flows out of fill plug hole. Then allow it to run out until it flows out slowly from bottom of hole. Install the fill plug and tighten.