Thanks for your reply. I see a variety of viscosities on the parts place shelf, even a multi viscosity one. The "Life long" nomenclature on the MB part makes me think it really wasn't intended to be changed. I think someone wrote in that there was no change time recommendation from MB. Be that as it may, with a small leak it has to be added to peridically. When you dropped the front diff. pan did you use a new gasket or re-use the one in place? My leak is not sufficient to worry about rebuilding or re-sealing the gear box so I would not ordinarily take the pan off.

At over 280M miles I have a couple of leaks. My independent repairman, who is very qualified, advises not to do a head gasket. There is no trouble there except for some expected leakage. I did have the front cover and valve cover gaskets done recently.

We can't find another car to replace this one with, it wouldn't be a new MB, we've looked at those and walked away and we want a station wagon but no one seems to make anything worth having. Life is tough sometimes.

Thanks for your help. srharvey