I had an identical problem with my 96 850. Turned out it was the rear camshaft seal, located
near the top of the engine on the right hand side, as you're looking at it. I cleaned the
flame trap, which was completely clogged, with a drill and the correct diameter drill bit in
it. Once the flame trap was clear and I replaced the seal, everything was just fine.
Not completely cleaning the flame trap means that internal pressure builds up within the
engine, blowing seals.
I originally thought it was the rear main bearing seal, but upon closer inspection, I saw that
the oil was dripping down the engine itself and exiting around the area you discovered the
oil, leading me to initially and erroneously conclude it was the main bearing seal.
Take another look at it; the cover to access the camshaft bearing seal is perhaps 2 - 3" in
diameter and is held in by three screws.
Good luck.
