I have a '96 750iL. Last snowfall I took my 15 yr old to a large parking lot to let her "play" on the slippery stuff to give her an idea how different it is to drive on snow and ice. While skidding around she approached red-line and since then I get the STOP! ENG OIL PRESS warning, but only at idle, and only when the engine has warmed up. It goes off around 750 - 800 RPM. I had the oil and filter changed shortly after this but it did not help.
Any ideas? It must be something common, because the same thing happened in my '93 Dakota with my other daughter.