Try new valve guide seals, and check valve guide to valve stem clearance at the same time.

I've listed instructions, as have others, in the past, do a search.

Bad valve guide seals will permit oil consumption of the range you have on an otherwise good condition engine. You will also have excessive blowby, especially if the guides are worn, too.

You will not see any oil smoke at this rate of consumption, except maybe a little blue puff when you start and after idling at a stop light.

And check the vent line from the vacuum pump to the intake manifold -- if you have a diaphram type pump, a leak in the diaphram will allow the pump to suck oil out of the engine and deliver it to the manifold!

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!