what benz you have but personally, i wont use oil lighter than that recommended by the mggr.

in my 616 and 617s i have always used rotella 15w40. sometimes in summer, straight 30w. i change oil and filter at 3000 pretty religiously.

my 350sdl i am using 10w40 mobil one and running 5k.

tom w

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.