I'm working on putting in a new timing belt kit and just got the plenum and coils out when removing the spark plugs I discovered one is soaked in oil. The tube the spark plug goes in has oil in it too. Is this from a bad seal in the valve cover? Do I need to plan on replacing that too? Odd thing is, the electrode looked burnt up so it seems oil was seeping down the threads into the combustion changer. Possible? What do you think?