If you haven't serviced your BMW's automatic transmission, you are driving around in a ticking time bomb. BMW advertises lifetime automatic transmission fluid - supposedly never requiring changing. Just like your engine, your transmission relies on its oil fill for cooling and lubrication. If you wouldn't drive your car for a lifetime without changing the engine oil, why would you do so with your transmission?
Servicing your transmission will extend it's service life as well as ensuring it continues to operate at its full potential. If your transmission is shifting slowly, sloppily, or it's overly loud, these are good signs that it's time to perform a transmission service.
Tools needed to complete this repair:
- Ratchet Set
- Torx Socket Set
- Torx Bit Set
- Fluid Transfer Syringe
- OBDII Scan Tool
- High Capacity Fluid Drain Pan
Parts needed to complete this repair:
Step 1: Lift your Car
Safety is key. Here at FCP Euro, we have the luxury of an automotive lift. Whether you are using a lift or completing this job on jack stands, take every precaution to make sure the car is secure. If using stands, place wood blocks or spare wheels under the car as an added backup.
Step 2: Remove Transmission Skid Plate and Heat Shield
Using an 8mm socket, remove the eight bolts that hold the trans skid plate in place. Then, using a 10mm socket, remove the remaining two bolts. The heat shield is held in place by three 13mm bolts. Make sure your car isn't hot since you'll be working around the exhaust. 
Step 3: Loosen Trans Fill Plug and Remove Drain Plug
Before you start draining the oil, loosen the trans fill plug using an 8mm socket. Doing this creates a vent and allows the oil to flow more freely. Now you can place your fluid catch pan under the transmission and remove your drain plug using a 10mm socket.
Step 4: Remove Transmission Pan Screws and Remove Pan
Using a T40 Torx bit, remove the twenty-four transmission pan screws. By leaving the screws opposite of the drain plug in place, you can drop the drain lower to more effectively drain the oil.
Once you drop the transmission oil pan, be sure the o-ring comes off with the pan.
Step 5: Clean Mating Surfaces
Often an overlooked step, cleaning the mating surfaces for the new transmission oil pan is mandatory. Without doing this, you risk having leaks - either immediately after completing this job, or not too far down the line. Simply use a lint-free rag or shop towels and make sure there's no debris or significant amounts of old oil.
Step 6: Install New Transmission Oil Pan
Since our F30 comes with the plastic transmission oil pan, our kit comes with the new pan that has an integrated filter. Before installing the new pan, make sure to lubricate the o-ring to ensure proper sealing.
Holding the pan in place, start all the T40 Torx screws by hand until they're just snug. From this point, you can follow the torquing procedure and torque all the screws to the specified 10N•m. The image below demonstrates the correct order. Once they're all tightened, it can't hurt to go around in the same order one more time to ensure that none loosened up.
Step 7: Fill Transmission
Before starting the fill procedure, make sure the drain plug is installed. The new pan in the kit has it pre-installed, however, it's worth checking. There's nothing worse than going to fill the transmission and watching oil spill out all over your garage floor.
Using our fluid transfer syringe, begin filling the transmission. We highly recommend using this syringe as the fill plug is difficult to access. A fluid transfer pump would work as well in this scenario. You want to fill the trans until it begins to overflow. Now you can loosely install the fill plug.
Step 8: Run Through Gears
Unfortunately, this next step requires you to take the car off the jack stands or your lift. With the car on the ground, you want to firmly apply the brake pedal, put your transmission in gear and run through all the gears. Do this until your car is up to optimal temperature. You can find this temperature listed on the side of the transmission oil pan. To determine if your car is properly up to temperature, use an OBDII scan tool that outputs this data.
Step 9: Final Transmission Fill
Using safe jacking practices, get your car up in the air once again. Just like before, continue adding more transmission fluid until it begins to overflow. Once it does, you can install the fill plug for the final time.
Step 10: Reinstall Heat Shield and Skid Plate
Now you're simply reversing the order of step two. I would wait until the car cools down since you will be working around the exhaust.
Having just done this service, the question of why BMW advertises lifetime fill arises. Doing this quick service every fifty-thousand miles will ensure that your transmission functions optimally for the course of its life. If you're wondering which kit you specifically need, click the link below and use the "My Garage" vehicle search. And as always, make sure to subscribe for more videos
