I changed my final drive fluid last weekend with Redline 75W-90 synthetic. Of course, this was after I drove all over town searching for the virtually impossible to find 14mm hex socket or allen wrench. I finally went back into the archives and found out that Autozone sells them, and sure enough they do. Got home and put the car up and low and behold, mine has 10mm hex not 14mm hex! So FYI, check your drain and fill plugs first and don't blindly trust everything the Bentley says.
1989 535iA, sharked, Mobil 1, Redline, soon to be tight like Rory's