You’re cruising along the highway when your Check Oil light comes on. As soon as you get home and the engine has a chance to cool off, you check the oil level. You’re surprised to discover that it’s low. You add a quart and forget about it. A few days or weeks later, the light comes back on and you add another quart. Your car is burning oil, and you need to figure out why.
How to tell if your car is burning oil
You don’t want to wait for the oil level to get too low to realize you have an issue. You can also tell there’s a problem if you see blue smoke coming from the exhaust pipe. The amount of smoke you notice is in proportion to how much oil is burning, so you know the owners of cars with billowing clouds following them should be worried.
What causes oil to burn
The reason oil burns is that it escapes from where it is supposed to be. As a car ages, different parts can become worn and not provide a tight seal around the oil. The oil leaks out and touches the hot components on the engine.
The worst case scenario is that your piston rings are worn. More oil is left behind in the combustion chamber where it’s burnt. However, this doesn’t usually happen with newer vehicles under 100,000 miles.
Another possible cause are leaking valve seals. They normally prevent oil from running into the combustion chamber. When they begin to wear out, small amounts of smoke come out of the exhaust when the engine is started.
When a PCV valve is worn, it also allows oil to seep into the combustion chamber. A defective or worn out PCV valve allows pressure to build up, which pushes out gaskets that are designed to seal out oil. A correctly working valve removes gases from the crankcase to prevent the pressure buildup.
Burning oil can lead to serious issues, including engine failure. If you notice a problem with your vehicle, get it checked out right away before the problem gets worse.
This article originally appeared on YourMechanic.com as What Does It Mean When My Car Is "Burning" Oil? and was authored by Joyce Morse.