A few years ago I bought a Euro 240D as a parts car. The previous owner had put the copper drain plug gasket that comes with an oil filter on the center stem. He also had them between the oil filter top and the housing at each bolt hole. He had given up on the car saying that it had an oil pan leak. I bought it expecting an oil pan leak, but it was leaking at the poorly sealed oil filter top.

It had held good oil pressure though, so I used the engine as it was for a short while.

Good luck,