I would "continue the "tradition." "

The only issue might be viscosity. Being where you are and what MB approves, 0W-40 and 15W-50 are the only two you may want to use.

0W-40 is still hard to find. It is only available at MB and Porshe dealers and Mobile distributors where it costs an arm and a leg (around $5-8/qt).

15W-50 is easier to find (Wal-Mart).

Some people use 10W30 (I do in the winter here in Michigan) but in theory, it is not one of the MB approved oil.