We have the same car, a 1980 240D. And they sound an awfully similiar. My car does not use as much oil as yours, about one quart every 1200 miles, but it does smoke. It generally does not smoke when started, but when at a stoplight it can be enbarrassing. Otherwise the car runs flawless.

My next item on my to do list is the adjusting the valves. Let me know if that makes any difference for you.