My 1993 320 TE (M104) smokes when run at high speed for prolonged periods. If I run for more than about 10 minutes at 90 mph or more, it pours a white/pale grey smoke from the exhaust. If I back off, it dies away.

The car has 179,000 miles. It is not using water. It does not seem to be using oil, or at least not much, certainly it has needed none over the last 1,500 miles. The head gasket was done about 20,000miles ago (for the second time) and there are no leaks. It does not smoke in the morning. It is fed a variety of good quality petrols, never the same station, rarely cheap supermarket stuff.

The car does vibrate about 80mph, not in the steering but from the drive line. The wheels have been balanced and balanced again so I suspect it is the propshaft and unrelated to the smoke.

I would be very grateful for any help at all. I am at a complete loss.

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JJ Rodger
2013 G350 Bluetec
1999 SL 500
1993 E300 diesel T
1990 190