Is there any safe oil to use in a 116 limited-slip diff from the early 1970's? The tag on the diff says, in German, "Use Special Oil". Can I just pour in some Mobil 1 90W or do I have to go to the Mercedes dealer?

I don't mind a trip to the dealer, but I was just wondering if something I already have in the shop might work.

Any one have any info on this?

Pooka