With the M5 laid up for the winter I'll do what I can in my garage.
Where to start? Replacing all fluids with new and known to be correct, and a good inspection underneath. The diff fluid that came out looked like shit - chocolate brown. New fluid and a test drive determined that the shaft input diff seal is leaking. I have some shop time scheduled for mid April for this and some other work.
New ATF in the transmission - the old also looked like shit.
New coolant flushed and filled with BMW blue. The old coolant was the green stuff (?) and didn't look bad, just green. Now I know and trust what is in there.
The oil was clean and golden, the sticker in the windshield listed 0w40. I replaced that with Redline 15w50. In the future I would not hesitate to use TWS same as in the S65.
I replaced the air filter and cleaned the MAF.
WTF here? I contemplated not even replacing this screen that is in line after the MAF. Why is this even here?
There is also a screen in place before the MAF so this second one seems useless. And if metal wire bits ever got sucked into the intake it could be a disaster for the motor.