I just purchased a 2005 c240 and really like the vehicle. One big problem was that once you get past 60mph on a steady cruise and then accelerate it left a huge cloud of smoke, I mean HUGE enough to slow traffic behind me. If found the problem after some thought. There was oil building up in the valve cover baffle on the passenger side due to sludge buildup in the drain at the back of the head. When I accelerate all this oil got sucked in through the PCV hose. I used some Berryman B12 to soak that passage and also used my fluid evacuator to suck it out a few times before it finally cleared out. PROBLEM SOLVED! The previous owner neglected the oil changes and developed this issue. I'm sure that's why he traded this thing in thinking he had major engine problems.

 

well if that was the case i would be changeing the oil alot for the next few thousand miles

 

Yeah. Give her a few oil & filter changes back to back to clean her up. Only use 229.5 oils.

 

Most definitely will change that oil a few times in much shorter intervals!