If Your Engine Oil Smells Like Gas, This Is Probably Why

Though necessary for your vehicle, engine fluids can become dangerous, especially when they get into and contaminate another fluid. When one kind of fluid mixes with another, it reduces the effectiveness of one or both of them, depending on how the contamination happened, and can cause all kinds of havoc in an engine. Oil in your coolant (or vice versa) is probably the most common and well-known kind of bad news fluid mixing, but what about others? What about, say, gas in your oil? Unfortunately for you and your vehicle's engine, it's a problem that could happen and not a cheap one either.

Engine oil and gasoline are two fluids that you never want mixing in your vehicle's engine. Anything getting in your oil is bad for your engine, but fuel contamination is especially bad for two reasons. One, it dilutes the oil to the point where it can't lubricate anymore. Two, it speaks to larger and more expensive problems with the engine or one of its related systems.

What kind of problems? Let's talk about it.

The biggest way to tell that you have gasoline in your engine oil, and frankly, the most obvious one, is your oil smelling like gasoline. How does the gasoline get down there, though? Well, the only way it can — through the cylinders. See, the biggest cause of gasoline/oil mix is fuel seeping past the piston rings and down into the oil sump. This can be caused by a number of factors including blowby, worn rings, incomplete combustion, or misfires.

Blowby is natural in all engines, but it gets worse as the engine gets older and the rings, pistons, and cylinder walls wear. Incomplete combustion and misfires both allow an excess of fuel to build up in a combustion chamber, which has nowhere to go but down. However, it can happen. Fuel leaking down through the cylinders to contaminate the oil is a sign that your engine is unhealthy and should be checked out pronto.

Removing the gas smell from your engine oil is pretty simple — you just change your oil. This just treats a symptom, however, and if you smell gas in your oil, you should have your car checked out by a mechanic to find out why your oil smells like gas. If you're lucky, and if you've caught it early enough, it should be an easy (though, potentially costly) fix.