Why is there oil on my spark plug?
You may find oil on a spark plug because: Too much oil was mixed with the gasoline. The piston rings (the component that seals piston and cylinder) are failing. If these rings are broken or failing in some way, they can let oil slip past the piston and get on the spark plug. What does it mean when you have oil in your spark plugs? The most common reason for oil on spark plugs is a leaking valve cover gasket.