Well, my non turbo 617 five cylinder diesel only made it to 208,000 when the timing chain broke. Since I rebuilt it, I put another 60,000 miles on it. Now it's using a quart of oil in 3,500 miles. When I opened it to rebuild it, there was cylinder wall taper on all the cylinders and fine cracks in the head. After boring the existing cylinder liners 0.25 mm oversize, installing a new set of Mahle pistons and buying a new head, the engine runs great. I also did replace all the exhaust valves as the stems were worn and the camshaft which had broken in two when the chain broke. I have a couple of 1985 300D turbo cars with nearly 200,000 miles on each one. No engine work on either of those yet. Mercedes diesels don't last forever but they do last longer than most anything else.