Its normal for the oil to drop down a good bit after driving fast but not all the way to nothing. The manual says .3 Bar at idle and 3 bar by 3000 RPM(in my opinoin that is not enough). Both of my cars will never drop below 1 bar or 15 PSI after driving at highspeeds for a long time but peg at the top when I speed up.

What kind of oil are you using?

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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

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