Diesels have the problem you describe. The question is how much lube oil
is consumed this way? A liter per 1,000 miles isn't nice but acceptable.
Basically too much air volume is blowing out of the crankcase and
carrying with it lube oil mist. Why is that happening?
If your motor has done say, 250,000 miles, it could need new rings.
Older diesels exhausted their vacuum pumps into the motor so a vacuum
leak somewhere in the car supplied such excess air. Does your motor (a)
have a vacuum pump and (b) if so does it vent into the motor?
Finally, is the engine's lube oil level BETWEEN the notches on the dip
stick. Some shops overfill and the excess is blown UP the air oil
separator's drain tube on hard acceleration (my experience).
Hope these thoughts help.
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