Engine Burning Oil

Ask any professional mechanic and they'll probably agree: Oil is the lifeblood of your vehicle's engine. It lubricates the moving parts of your engine while also minimizing heat. If you notice a gradual decrease in the amount of oil in your engine, though, you might be wondering whether it's normal. Whether you drive a car, truck or SUV, it's not uncommon for vehicles to burn oil. However, this doesn't necessarily mean that it's a normal phenomenon.

The Basics of Engine Oil

Although there are exceptions, most vehicles use about 5 to 8 quarts of engine oil. Generally speaking, the more cylinders an engine has, the more oil it will use. A 4-cylinder engine, for example, may use 5 quarts of oil, whereas a six-cylinder engine may use 6 or 8 quarts of oil.

Engine oil is stored at the bottom of your vehicle in a component known as the oil pan. When you start your vehicle, a pump will pull oil from the pan, at which point it will enter the crankcase where it lubricates your engine's moving parts. But over time, you may notice a reduction in the amount of oil in your vehicle's engine.

External Leaking vs Burning Oil

If your engine is burning oil, it technically has a leak. This isn't a normal leak, though. Rather, it's considered an internal leak, meaning the oil is leaking into your engine's combustion chamber where it's burned off with the gas and air.

An external oil leak means your engine is leaking outside of the engine. If your vehicle is suffering from an external oil leak, you'll probably discover pools or puddles of oil on your driveway. If your engine is burning oil, on the other hand, the only sign you'll see is an ever-lowering oil level on the dipstick.

Why Engines Burn Oil

Engines can burn oil for a variety of reasons, one of which is bad valve seals. When your vehicle is running, oil will circulate around the inlet valves. While there are seals in place to prevent oil leaks, they generally don't last forever. Depending on the mileage of your vehicle's engine, the valve seals may be worn to the point where they can no longer contain oil. And once a valve seal fails, oil will leak into the engine's combustion chamber.

Another common reason engines burn oil is bad or worn piston rings. Like with valve seals, piston rings prevent oil from entering the combustion chamber. When piston rings fail, your vehicle will burn oil.