Was riding in daughter's '83 300D yesterday and noticed that the oil pressure was reading 2 bar at 60 mph. After telling her to pull over and turn off the engine, I asked her if she had noticed the oil pressure being low. She said that sometimes the gauge pegs the bar and sometimes it doesn't. She's been driving that way for a few months!

She started the engine and it went to 1.5 bar, higher than I remember the idle pressure being when I drove the car. Back on the road, the gauge swung between 2 and 3 bar.

Any ideas? Mobil 1 15W50 level is OK. Has an approved filter. No significant leaks.

Has anyone put a test gauge together, and if so do you recall the thread size on the filter cannister?

I've searched the archives but haven't found a similar condition

Thanks,
Wray