Glossary
Oil dilution
Fuel mixed into the engine oil, which thins the oil and makes the oil level on the dipstick rise.
Oil dilution is what happens when fuel that has not burned finds its way past the piston rings and into the crankcase. Fuel is a solvent, so the oil becomes thinner than it should be and protects the engine less well. The extra volume also pushes the dipstick reading up, and the oil smells of gasoline.
It is most common on direct-injected engines that spend a lot of time cold: repeated cold starts, short trips and cold weather all make it more likely.
Guides that use this term
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