After owning my 91 M5 for a few month, I tried for the first time to replace spark plugs.
On plugs # 5 and 6 when I pulled the long cable tips I noticed that they were all soaked in oil and so were the tops of spark plugs. The rest of the plugs looked clean and dry. Is this most likely a valve cover gasket leaking or something more serious?
After replacing all plugs there was a little blue smoke from the tail pipe for a short while (probbably because some of the oil got into cylinders) but car runs fine, Any advice?