FWIW, I was able to remove the fill plug with a machined down allen key.

Thanks to all on this thread I gathered the courage and change the transmission oil. I used a transmission jack to lift up the transfer case - about 1.5 inches is all you need to get a T40 wrench to loosen the bolts.

I have a question - I did not remove the megatronic, just replaced the oil pan, and filled back about 4.5 liters. After warming up I drove the vehicle and then when I opened the fill plug to recheck the level, oil gushed out and I quickly plugged it back. Does this mean the transmission has enough oil, as I mentioned about 4.5 liters? Appreciate your responses and thank you in anticipation.

Did you pull the plug with the engine running? If so, the oil should run out (a small stream), but not gush out. If you opened it with the engine off, oil will definitely gush out and you will have to do the fill procedure again as you might have let out enough fluid to be low.

^ Correct. When running the oil pump in the trans pulls in (up?) oil and distributes it throughout. If you check when off...welll, the TIS tells you to check WHEN running and AT a specified temp range.


Also 4.5 L seems low. If you did this all with the engine off and cold. that could explain things...

Also, many people mistakenly think the transmission should be at full operating temp when checking the level. Depending on the transmission, it's actually just barely warm (85-125F). Essentially, by the time I can start it up and crawl back under the car to do the final fill, it's already in range. If you're slow, you'll miss the window as the transmission warms up pretty quickly.

AM.

Update: I competed the fill procedure and could get another 0.5 liters in. The total oil fill capacity without removing megatronic unit in my case was approx. 5.1 liters. Thanks for everyone's help.

At what mileage interval should this procedure be carried out? Does it help to make for smoother shifts, or is it just preventative maintenance to stop it breaking in the future?

My car shifts smoothly if I accelerate slowly, but on any kind of throttle that requires the car to move a little briskly in the lower gears, the shift can be very quick and leave me with a feeling that it slipped/jerked into the next gear, rather than shifting in a controlled motion.

ZF says fluid and filter every 70-80k miles. I did my first fluid and filter/pan change at around 120k miles, fluid only at about 170k miles and will probably do the fluid and filter/pan again at 200k. I've settled on 50k miles for my transmission. Fluid and filter - if equipped - changes are just part of basic maintenance. Or just go with BMW's advice and treat the fluid as lifetime fill.

Thanks man, I'm pretty much bang on in terms of being due for it. I'm on 75k N62 4.8

I'll order the parts online for tackling in the new year :)

Yeah, just drop the pan, replace it (filter is integral to the pan), replace the lost fluid with new fluid, reset transmission adaptations, and then drive it easy for 100 miles or so to let it relearn.