Check the oil filler cap for leakage. Only happens at speed, can lose quite a bit of oil with only traces on the floor.

Valve cover gaskets need replacing on a regular basis on these cars, they get very hard and dribble. The leak will be worse with Mobil 1 than with dino.

I've not had any real problems with leakage on any of the cars I've swapped over. Once I replaced the oil filler cap on the 300D, I use less than a half quart in 6000 miles. The TE seems to be running about 3000 on a quart these days.

Peter

__________________
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!