Poly - Thread Finder
With the proper MB scan tool there is a fairly easy, but somewhat coarse test routine for compression using cranking speed. That may give an idea if the compression on a cylinder(s) is low as compared to the others.
Something tells me when you are using "gallons" of oil the spec of the oil may not matter!Running a 2007 and up on any oil that isn't 229.51 approved is just adding to the problems. What do you think happens to the crankcase pressure inside the engine when the emission system fouls up from the excess additives in non 299.51 oil? Guess what excess crankcase pressure can cause?
Unless somethings has changed today...there is no Rotella (or anything at TSC) that is 229.51 approved. Just because it says it is emission friendly oil...means nothing to the MB emission system. It has much higher requirements for friendship.
I suspect you are loooooong past this being fixable without a re-build and suspect the previous owner neglected/destroyed this for you.
Going to take it back to the shop when I get back for the 4th time.Studio, just noticed you mentioned driving 'all day' and don't see any smoke. Stupid question maybe but have you driven much at night yet? I owned my van a couple months before I was out in it at night. I too thought my van didn't smoke, the cars' headlights behind me at night illuminate a never ending cloud of smoke.