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How does water get into motor oil?

“How does water get in the engine oil? Does it blow past the pistons or valves? Does water in the oil indicate the possibility of a blown head gasket?”

Paul Lott, Bryans Road, Maryland

Answer

Water can get into the oil two ways. You generally don't have to worry about one of the ways if you drive your car enough to burn off the water during normal driving. This drives off the moisture that simply comes from your engine breathing when it is not being used (cold air enters a hot engine and water condenses) and from combustion byproducts. The second more destructive route is through a coolant leak due to a bad gasket, an engine crack, etc. This amount of moisture is generally going to cause serious engine issues including loss of power, oil sludging, etc. Consult your mechanic when in doubt.

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