New to forum, I have a 2004 E83 with 87k. I am second owner. Car has been maintained very well, I replaced spark plugs and coils with hi perf plugs and coils about 300 miles ago. Old plugs were in good shape no oil. Car ran fantastic after upgrade. I was at a stop light idling and the car starting running extremely rough, service engine soon light went on. Checked today got oil on threads and appears to be in the well,. Any thoughts? valve cover gasket, O-rings, valve guides???????