Do you get blue smoke on startup? This usually means bad valve guide seals, not too surprising at 160,000 miles.

What do you mean by excessive smoke? Does the car behind disappear in a black cloud, or do you just see a flicker above the deck lid? Latter is normal, you should see some smoke at full throttle/full boost.

If you are seeing bluish gray smoke, not black, then you are looking at either excessive blowby (easy to check) or leaking seals in the turbo. The latter will soon result in LOTS of blue smoke, and serious oil consumption.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!