A buddy of mine has a 1987 w126 300sdl with the om603 engine, it the original engine with the original #14 head. he was on the highway and all of a suddn the car just started heavily smoking. i went over to check a few basic thing and i found;

No coolant consumption, no oil in coolant. no coolant in oil. SIGNIFICANT LOSS OF OIL ( low level) , pressure good , drove it around the block, good power. Thought it might be the turbo seal so I took off the cross over pipe, but no smoke either way. pulled the oil filler cap and no smoke( no blow by )

Im a little stumped. What could it be? Hes loosing a lot of oil and its out the tail pipe, white in color. if the turbo seal goes bad can it go out the turbine side? Is it the head? or gasket ? in a spot where oil just doesnt mix with coolant?

please help