Why Is My Car’s Engine Burning Oil?

Engine oil lubricates the internal moving parts of your engine and is critical to the operation of the engine.  That’s why you don’t want to let your engine oil levels get low because you’d up your chances for damage to the engine to occur.  But what if your car is burning oil, what should you do then?

If you suspect that your car’s engine is burning oil there’s likely an issue with worn piston rings, a blown head gasket, or a bad PCV valve. But you’d also want to rule out that you don’t actually have an oil leak somewhere fooling you into thinking that your engine is burning oil.

What should you do if you know that your car is burning oil?  What are the main symptoms of a car that is burning oil? Keep reading to find out.

Top 3 Reasons Why Your Car’s Engine Is Burning Oil

1. Worn Piston Rings

Each piston inside of your car’s engine will have a piston ring that goes around the outside edge of the piston.

The main purpose of a piston ring is to provide a seal between the piston and cylinder wall that prevents oil in the oil pan from reaching the inside of the combustion chamber.

Over thousands of miles of use, those piston rings can become worn down by the friction created from sliding up and down thousands of times a minute against the cylinder walls of the engine.

This friction between the piston rings and can eventually cause the piston rings to wear not seal as well as they used to when they were brand new.  This can allow engine oil to get past the seal of the piston rings and into the combustion chamber which can be one reason why your car is burning oil.

2. Blown Head Gasket

The head gasket in your engine is designed to create a seal between the block and the cylinder heads of the engine.  If your head gasket becomes damaged or starts to leak this can cause engine oil to leak outside of the engine which can cause your engine to consume oil at a faster rate.

A blown head gasket can also lead to coolant getting mixed in with your engine oil which is not good.  To learn more about what it means to blow a head gasket and how much it costs to repair one check out my other article (click here).

3. Bad PCV Valve

The Positive Crankcase Valve (PCV) valve on internal combustion engines is designed to ventilate the crankcase of the engine.  This allows some of the gases from the combustion chamber to be sent through the PCV valve into the intake manifold to be eventually sent back into the engine.

Over time the PCV valve can get stuck in the closed position or fail to open properly.  When this happens pressure in the combustion chamber can’t escape which then creates excess pressure inside of the engine.  This excess pressure can lead to blown engine seals/gaskets and can push engine oil into the engine cylinders, causing excess oil consumption or your engine to burn oil.

Bonus: Engine Oil Leak

Another reason why your car may be burning oil or using too much oil may not be a problem with the engine at all, it could be that your car is actually just leaking oil.

When engine oil is drained out and eventually replaced if the drain bolt on the oil drain pan is not tightened properly it can allow engine oil to slowly leak from the oil drain bolt.

In most cases, if your oil drain pan bolt is leaking oil you would be able to spot the oil around the oil drain bolt.  However, if your car has a cover beneath the oil drain pan this sort of problem may not be that easy to identify without first removing the engine cover to inspect the underside of the engine for oil spots.

What Are The Symptoms of an Engine That is Burning Oil?

1. Low Engine Oil Levels

The most obvious clue to indicate that your engine is burning oil is low engine oil levels.  This low oil level could be indicated on the oil dipstick or if your car is newer it can warn you on the dash when engine oil levels get too low.

2. Smoke from Tail Pipe

Another symptom of an engine that is burning oil is smoke coming from the exhaust.  Like I mentioned earlier, as your piston rings wear down it can allow oil to pass by the piston rings and into the combustion chamber.  This oil would then be forced out through the exhaust port with the other exhaust gases in the combustion chamber and eventually make their way out of the exhaust in the form of smoke.

Is It Bad If My Car Needs Oil Added In Between Oil Changes?

Under normal circumstances, it’s fine if your engine burns a bit of oil between oil changes.  Many vehicle manufacturers say that a quart of oil may need to be added to their engines between oil changes.  But if you find yourself having to add multiple quarts of oil in between oil changes you likely have a problem with your car burning or leaking oil.

Is It Bad To Drive A Car That Burns Oil?

The answer is it depends on your current situation.  If you have a blown head gasket then yes, driving with a blown head gasket can cause damage to your engine and you shouldn’t drive the car.  But if your car is burning a bit of oil between oil changes attributed by normal wear to the engine then continuing to drive the car is fine.

You’d just want to continue to monitor your engine oil levels so that they don’t get too low to cause damage to the engine.  Engine oil is designed to lubricate the internals of your engine.  If the oil level gets too low inside of your engine it will lead to increased friction, heat, and eventually increased engine wear.

How Much Does It Cost To Fix a Car That Burns Oil?

The cost to fix a car that burns oil will come down to what is actually causing the car to burn oil as some repairs will be more expensive than others.  A new PCV valve should cost less than $20 and it’s typically easy to locate in your engine bay.

However, if you need to have new piston rings or a new head gasket installed then you are looking at thousands of dollars to have your engine disassembled in order to reach the piston rings or head gasket to replace them.

Head gaskets will typically cost in the range of $30-$50 for just the replacement head gasket. Replacement piston rings typically cost around $100 for the replacement piston ring parts. The real cost comes from the amount of work it takes to disassemble an engine to be able to reach them to replace them, as it can take quite a few hours to disassemble an engine.

What Happens If You Don’t Get The Burning Oil Problem Fixed?

Allowing your car to continue to burn oil can have dire consequences on your engine.  Depending on the severity of the issue you may be impacting the life expectancy of the engine by not getting the burning oil problem fixed.

How Many Miles Should a Quart of Oil Last?

How long a quart of oil should last between oil changes has been up for debate for a long time.  Most people would say that one quart of oil should last in between oil changes and that if more than one quart of oil needs to be added between an oil change that there is a problem.

Vehicle manufacturers vary widely on their responses regarding oil consumption.  Some vehicle manufacturers say that it’s normal for you to have to add a quart of oil every 1,000 miles or so.  While others say that a quart of oil may have to be added every 2,000 miles in their engines. So it really depends on your specific vehicle manufacturer and what they say is within the accepted oil consumption range.

Is It Expensive to Replace Piston Rings?

Yes, it can be expensive to replace piston rings in a car because of the amount of work required to tear down an engine to be able to access the piston rings within the engine.

Piston rings themselves aren’t that expensive coming in at around $100 for replacement piston rings but to replace the piston rings means that you have to be able to access the positions which also means tearing down the engine.  As you can imagine there is a lot of work involved with taking apart an engine to be able to reach the pistons inside.

How Do I Know If My Piston Rings Are Bad?

One way to tell that your piston rings are bad is by smoke coming out of your tailpipe. Now, just because there is smoke coming out of your exhaust doesn’t mean that your piston rings are bad but it can be an indicator.  This is because when piston rings go bad they allow oil from the bottom of the engine to get into the combustion chamber and then exit the car in the exhaust in the form of smoke.

Another indicator that your piston rings are bad is a loss in compression in the engine and an increase in piston noise.  Since piston rings are designed to create a seal around the piston if the piston ring fails this can cause the compression in that piston to be reduced.

The way to check for a loss in compression is to have a compression test performed on the engine to test out each individual piston for a loss in compression.

Related Questions

Can I sell my car if it’s burning oil? Yes, you can still sell your car if it’s burning oil.  But the best course of action would be to tell the person you are selling the car to the problems that you are having with oil consumption.  That way the person buying the car understands all of the problems with the car before purchasing it.

Can Bad Spark Plugs Cause Burning Oil? Spark plugs can become fouled with use which means that they won’t work as well as they used to. But typically spark plugs aren’t going to be the culprit when it comes to excess oil consumption.  Bad spark plugs usually will result in issues with excess fuel consumption.