I'm using Schaffer's Parasynthetic racing oil in mine. Zinc, Moly and some other proprietary additive.
Carl,
0W-40 Mobil is factory fill for Mercedes and those are the only places I have seen carry it. Could try Star Motor Service in WA. We used to stock it in 55 gal. drums when I was parts manager there. They may pump it into a jug for you.
__________________
Jaime
|