Mercedes Technical Service Bulletin 00 053, issued 10/1/93, lists "Factory Approved Service Products".

For rear axle differential (not limited slip) the only oil listed is MB Hypoid Gear Oil MB part no. 000 989 28 03.

For coolant, the only approved product is MB Anti-Corrosion/Anti-freeze MB part no. Q 1 03 0002

For brake fluid, the only approved product is MB Brake Fluid (DOT 4 Plus) MB part no. 000 989 08 07 10.

What give with that? Mercedes has approved several types of engine oil and ATF, but seems to think that only Mercedes fluids will work in the differential, radiator, and brakes. I have been using Castrol LMA in my 1979 300SD and it doesn't seem to mind.

For the 1985 300D that I just bought, I think that I will run down to the dealer and get the differential oil and antifreeze and stick with the Castrol in my brakes.