Wolfe - that Pdf is dated 11/2008. But it talked about the M1 model as in the ORIGINAL M1! So it has some age to it.
One thing is for sure:
Castrol SAF-XJ is specially designed to work in M lsd's. It says that right on the Castrol bottle.
In that Pdf it also says "normal" diffs should use:
SAF-XO It also says these cars can be identified by a centeral fill oil plug on the diff.
BUT... on a 135i the "fill hole" is an offset type? It sits to the right side. So... ?
Perhaps, you can use SAF-XJ in non-lsd cars. But not the other way around. ? Or perhaps the 135i does indeed have a quasy LSD? Since I am almost 100% sure my parts guy said to use Castrol SAF-XJ. Perhaps I should go recheck this before I change the diff oil.
Dackel