I would say that it is taking too long to bring up the oil pressure.

I have the m116 engine (420 SEL), when the outside temp is above 32F, it jumps to 3 bars on starting. If engine temp is 80c, oil shows about 1.3 bars at idle. Engine temp. 100 or above, oil shows 1 bar.

Originally when I bought the car, oil would dip to .5 bar on a hot idle, but upon acceleration would come to 3 bar immediately. Here is what I did to get the oil pressure up.

1. Oil pan was dented. While replacing oil pan, I saw bottom of oil pump tower was actually broken. The rubber was rock hard. I replaced the rubber oil pump bottom sucker. Replaced oil pan, and gasket.

2. Popped the valve covers. Removed each and every HLC. All of them had thick black goop in the bottom. I pressed down on some of the them, and black tar like substance came out, which also felt gritty, like sand. Replaced all HLCs. Also there is a tiny hole about 1/8" in diameter on the rim of each HLC socket. It too was filled with black oil. I stuck a thin plastic tube into the duralube aersol can and flushed out those tiny holes. I could see the duralube foaming clear up through the adjacent holes. Replaced HLCs, rockers, checked basic position, replaced valve covers.

3. Changed oil to 5W50 synthetic, new filter, and now great oil pressure!!

In the winter, when the outside temp. -20c or lower, it does take 2 sec. to come up to 3 bars.

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1989 420 SEL