Why Is Your Car Burning Oil?

DIY

Engines and Components

Chris Tonn

November 03, 2023

Chris Tonn

November 03, 2023

Oil lubricates every moving part in your engine, keeping metal pieces from grinding against each other. Check your oil level regularly - opens in new window or tab.—as you should—and you might notice the oil level dropping. If you can see oil drips on the pavement, there’s a leak.

But if there’s no outward sign of leakage, then your car’s engine is probably burning oil.

In many cases, if a car's burning oil, the repairs go beyond the skills of a home mechanic. However, some oil burning problems are an easy fix—so read on.

Shop now for PCV valves - opens in new window or tab.

Causes of Burning Oil

Typically, oil burns as part of your engine’s combustion cycle. But sometimes oil gets into the cylinder chamber and is burned during the combustion of fuel and air. That’s not good.

Burning oil can cause damage to the catalytic converter and oxygen sensors downstream of the engine. If the engine burns too much oil and the proper level of oil isn’t maintained to make up for the loss, internal engine damage can occur.

While some oil burning typically occurs as an engine wears over time, some brand-new engines can burn oil, too. Automakers say that it’s perfectly fine for an engine to use a quart of oil in as little as 1,000 miles of driving.

Modern engines often use direct fuel injection, which sprays liquid fuel directly into each combustion chamber. Sometimes, this fuel mixes with the oil that lubricates the cylinder, causing both to be burned and the oil level to drop. Also, modern fuel-efficient engines often use thinner oil that slips past seals and piston rings into the combustion chamber. That’s why you need to regularly check your oil level no matter how old your vehicle may be.

Signs of Trouble

There are telltale signs that your car is burning oil. If you notice the levels dropping when you check the oil, you might also see these three things:

Low oil pressure light or gauge - Your car’s dashboard might indicate that the oil pressure is too low. Most cars have a low oil pressure light that illuminates, and some have an oil pressure gauge. If the light or gauge is indicating low oil pressure - opens in new window or tab., you need to stop the car and investigate the cause.

Blue-tinged exhaust - Sometimes, if the engine is burning oil, the exhaust coming from the tailpipe will have a subtle blue color. It takes a lot of oil in the exhaust to turn it blue, so this can indicate a serious problem.

Burning oil smell - If enough oil hits hot surfaces within the engine, it can cause a pungent burned smell.

Checking car engine oil level on dipstick

There are more serious possible causes for your car's engine to burn oil. Some require significant repairs.

Clogged or worn PCV valve - The positive crankcase ventilation system ensures that excessive pressure buildup in the engine’s crankcase is safely ventilated to the atmosphere. If this excessive pressure is not dealt with, it can cause oil to be pushed past piston rings and other seals. If the PCV valve - opens in new window or tab. is clogged or otherwise worn, this excess pressure can cause oil to escape.

Worn or broken piston ring - Piston rings - opens in new window or tab. create a seal between the piston and the cylinder wall. During normal operation, oil should remain below the piston ring. If the ring is worn or broken, oil can seep past the seal and get into the combustion chamber, where it burns.

Worn valve seals - As the valves move up and down during the combustion cycle, they slide within seals, keeping oil out of the combustion chamber. If the valve seals - opens in new window or tab. wear, oil can seep down into the cylinder and burn.

Leaking head gasket - The head gasket - opens in new window or tab. creates a seal between the cylinder block and cylinder head. If there is a leak, oil can seep into either the combustion chamber or into coolant passages.

Worn turbocharger bearing seals - Many modern engines use turbochargers to increase performance while maintaining fuel efficiency. These turbochargers have impellers that spin at incredibly high speeds. The bearings within these impellers are often cooled with oil, but if the bearing seal wears, oil can easily be pushed past the seal and out the exhaust.

How to Fix a Burning Oil Issue

Unfortunately, most of these oil-burning issues are internal to the engine, requiring significant repair to fix.

A man installing a Positive Crankcase Ventilation PCV valve on a 1963 Buick Nailhead V-8 engine — Installing a positive crankcase ventilation PCV valve on a 1963 Buick Nailhead V-8 engine

A PCV valve is often easy to replace - opens in new window or tab., so if your car's burning oil, this might be the first place to start.

However, replacing piston rings, head gaskets, or valve seals often requires opening up the engine. So if you aren’t confident in your abilities, it’s likely best to rely on an experienced mechanic.

No matter what car you drive, it’s critical to watch your oil levels so you can correct any oil-burning issues before they cause further damage.

About the author

Chris Tonn

Some enthusiasts say they were born with gasoline in their veins. Chris Tonn, on the other hand, had rust flakes in his eyes nearly since birth. Living in salty Ohio and being hopelessly addicted to vintage British and Japanese steel will do that to you. His work has appeared in Hagerty, The Truth About Cars, Reader's Digest, AutoGuide, Family Handyman, and Jalopnik. He's currently looking for the safety glasses he just set down somewhere.

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This article is meant to provide general guidance only. Automotive maintenance, repair, upgrade, and installation may depend on vehicle-specifics such as make and model. Always consult your owner's manual, repair guide for specific information for your particular vehicle and consider a licensed auto-care professional's help as well, particularly for advance repairs.