Is it bad to have oil on your spark plugs?

The most common cause of oil on spark plugs is a leaking valve cover gasket. Once the seals around or next to the plugs start to leak, oil can seep into the spark plug wells. You do not want this oil to get into the cylinder. This decreases the space inside the combustion chamber, which can cause hydrolocking. Once you fix the seal, remove the spark plugs and place rags over the plug wells. Crank the engine. This will push the oil out onto the rags. Once there is no more oil coming out of the plug wells, you can reinstall the plugs.

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