This tech information comes from Jim Blanton, owner of Blanton Transmissions.  Jim is a well known and respected individual in the area of BMW transmissions and differentials.  Blanton Transmissions performs rebuilds and upgrades on BMW transmissions and differentials to each individual owners specifications and requirements.  Jim Blanton can be reached here:

Blanton Transmissions
1427 West 9th Street
Kansas City, MO 64101
816-221-8584

jblanton@sky.net

Differential Lubricants

Limited slip differentials, especially ones that have a higher than stock (25%) static lock, require the "friction modifier" or "limited slip additive" that is sold both separately and already installed in the lubricant.  Oil drain intervals will depend mostly on how much track time the diff sees, but I wouldn't go longer than one year.

Transmission Lubricants

For manual transmissions, I recommend MTL (MT-90, a higher viscosity version for hotter climates) but only a GL-4 lubricant.

Why does Jim Blanton like Redline?

Redline is not the only lubricant that works, but for the 15 years or so that I have been using it, it has had a flawless track record.

Red Line Synthetic Oil Corporation
6100 Egret Court
Benicia, CA 94510
800-624-7958

http://www.redlineoil.com

Thanks for the information and sharing your experience, Jim!