Get two bottles from the dealer, that will cover you. Use a something to suck the old oil out. It will likely be green (normal). New it's clear. The green comes from the wearing of the nose drive coupler. Being green doesn't mean the drive coupler is bad.
PN is 12345978 (I think). Just ask for supercharger oil. The M62 and M90 use different amounts but both are under 2 bottles. Fill to the bottom of the hole on level ground. It's about $8 a bottle around here.
I change it every 25k miles. The blower will normally last about 70-100k before it sounds like rocks are rolling around in there. It's especially noisy with the intake hose off and the blower is cold.
If you are getting that noise (rattle, rattle, rattle), remove the belt, grab the pulley and lightly turn it back and forth. If you feel any play, the coupler is worn out. They are about $30 from ZZP and can be installed by the backyard mechanic. Outside of that, I have two over 200k miles and only the couplers wore. Of course if you get rotor lock, you'll know it when the belt burns and then snaps. That's rare.
[This message has been edited by TK (edited 01-19-2004).]