Chances are, its the oil pump failure. Replace it RIGHT AWAY unless you want to throw the car away. I had the same issue, low oil pressure at idle, and lower in the summer heat and it was the oil pump. I didn't replace it in time and it lead to bearing failure and the motor got junked. Started to knock and then it was toast and on its way to the junk yard.

Do not drive the car any more until you decide what you want to do with the car. Good luck and let us know what it ended up to be once you know for sure.

-=>Raja.

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1983 MB 190E, bought from Germany and shipped to the US in 1986.