If my conversion is correct, your oil consumption is 3.65 quarts of oil in 600 miles.... or a quart every 165 miles.

I would say this is excessive!

Sounds like the valves are worn out or severely out of adjustment.

Have this checked ASAP.

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William
76 240D (W115) - 550K miles
78 300D (W123) - 200K+ miles