Quote from Scott9999 above:
"Rumor has it that the final drive is a Torx Plus T40, not a Torx T45, but I haven't had time to plug in my DVD player and bring up the BMW manual to verify one way or the other (lol, it's like a half hour process to use BMW dang manual, and I'm not even sure it would tell me that info). Anyhow, I got it out with a Torx T45, which seemed to work out OK, but it was stiff. If it's actually TP40, that may explain the difficulty I had with the drain plug. (I've read many "sources" to positively affirm both Torx and TP, as THE BMW R1200 GS/RT final drive oil plug. (I even went looking for parts, and the $23 plug is probably part # 33117705854 for my 2018 RT, but the parts catalog doesn't say whether it's a TORX or TP.)
Anyhow, I've got the TP wrenches on order."
I contributed to the misinformation about this Torx Plus 40 thing about 2 years ago and try to correct what I got started whenever I can...not trying to hijack this thread...
The Final Drive drain plug needs a T45 to remove. No Torx Plus bits here.
If it is difficult to remove the drain plug after about 1.5-2 turns, it's because the metal on the final drive itself has been flattened out and flared into the path of the threads of the drain plug on removal.
So, as you turn out the drain plug, and it gets past the thickness of the O-ring, the threads on the plug run into the deformed metal of the FD housing and you are forcing the drain plug out from that point on.
Once you do get it out, you can fix the situation by running some thread taps into the drain threads on the Final Drive to "chase" them clean.
I use a 2 tap set that has a starting tap and a bottoming tap. The starting tap is helpful because the first thread is the one that is "bunged up" from the drain plug being tightened into the final drive housing. Using a torque wrench on this and all the fasteners on this bike is essential...there is no such thing as a calibrated elbow to make sure this is installed to the correct torque.
Using some grease in the flutes of the tap will capture the swarf (metal cuttings) from the sharp teeth of the tap and ensure that none of it gets up into the gear housing. Then use the bottoming tap to clean the remaining threads only to the thickness of the housing and not into the perimeter of the ring gear. Follow this up with a good cleaning with some cotton swabs and the drain plug will not only start easier, but also run into the full length of the threads smoothly as it should.
Here is the link to the 2 piece set of M12x1.0mm taps that I use.
I'm just trying to keep the correct information about maintaining our bikes out there and limit "Internet Myths and Misinformation".