Too low for 20 W 50 oil -- you may have a bad seat or ball on the pressure relief valve, or a bad gauge. Easy to check, have your tech put a real mechanical pressure gauge in place of the sending unit.

You really need to have 0.3 bar minimum pressure at idle, else extended idle will cause the main bearings to fail.

Real pressure that low indicates a leaking pressure relief valve in the oil filter housing, worn main bearings, or a worn out oil pump.

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!