Car Has High Oil Consumption? 9 Common Issues & Fixes

All engines consume a little oil. It’s a little-known fact, but most will lose or consume ½ quart of oil for every 5,000 miles of driving. Most new cars consume less than that, but some of the older models on the road are known connoisseurs of your favorite oil brand.

If your car consumes more than 1/2 quart every few thousand miles, it should be considered as high consumption. Want to know why it happens? We’ve tracked down the 9 most common reasons and how to fix them.

Oil consumption is just one issue with used cars. Check out our article on what to look for on your next used car purchase.

#1 – The Biggest Issue Is Worn Seals and Gaskets

Every engine has many connections between components that require a gasket or seal to keep oil inside the engine. Over time these gaskets and seals can degrade from heat, become brittle from exposure to oil and other fluids, or be damaged in contact with other parts.

Gasket and seal materials have become better with technological advances in the last two decades, but earlier engines may have suffered many gasket failures due to poor materials.

How to Fix It

Seals and gaskets should keep oil inside the engine, so if they start to leak, they should be replaced ASAP.

Some gaskets such as a valve cover gasket are on top of the engine which makes them easier to replace. Others, like the oil pan gasket, are on the bottom of the engine and aren’t as easy to replace. You may need to remove the engine from the car to replace one of the gaskets on the bottom.

We have more here on typical reasons for head gasket problems in cars.

#2 – Your Engine Has Worn Piston Rings

The pistons in your engine have rings that lock into grooves around the circumference of the piston. These rings are meant to keep oil from entering the combustion chamber and being burned in the combustion process. They can wear over time and develop micro-cracks that allow oil to seep by and slowly be consumed.

How to Fix It

Worn piston rings are a difficult job to fix.

The rings must be removed from the pistons and replaced with new rings. This requires the pistons, crankshaft, and more components to be removed from the engine. The engine should also be removed from the car before starting the work. It’s a big job to undertake, and it may be best to leave it to a seasoned pro who has all the correct tools and knowledge to complete the work quickly and efficiently.

#3 – Your Engine Has Scored Cylinder Walls

Your engine has polished cylinder walls that your piston rings slide against as the piston goes up and down during the combustion cycle.

These polished surfaces can wear over the life of the engine and micro-cracks can form in the surface that allows engine oil into the combustion chamber. The oil is then slowly burned and consumed as your engine runs, and you may find a quart or more missing at your next oil change.

How to Fix It

Scored cylinder walls can be temporarily repaired with a pour-in oil solution that bonds to the cracks in the cylinder walls.  The solution can reduce oil consumption, but it isn’t a permanent fix. To fully repair the cracks in the cylinder walls, the engine must be disassembled, and the cylinder walls polished again.

If the cracks are too large, the cylinders may need to be bored (enlarged) with a larger diameter piston used during reassembly.

If the engine cylinders can’t be enlarged, the engine block would need to be replaced.

#4 – You Chose The Wrong Type of Oil For Your Engine

Each engine manufacturer recommends a certain weight of oil, and there are multiple types of oil at your local auto parts store to choose from. The internet is full of bad advice like adding diesel engine oil to a gasoline engine or changing the engine oil weight from a low viscosity to a higher viscosity to fix an oil leak.

Changing from conventional oil to a synthetic oil can in an older engine can also cause high oil consumption as older engines aren’t designed for the characteristics of newer synthetic oils.

All of these pieces of bad advice can cause higher oil consumption because you chose a different type of oil for your engine than what is recommended.

How to Fix It

If you chose a different type of oil than the manufacturer recommends, it’s easy enough to drain from the engine and replace it with the correct type of oil. You should also replace the oil filter to ensure you remove all of the wrong type of oil.

#5 – You Keep Missing Your Oil Change Frequency

We’ve all done it. You’re busy and go over your oil change frequency by a few hundred miles. 500 miles over isn’t going to cause a dramatic issue with wear and tear on your engine. 5,000 miles over will cause your engine to wear more than it should. As engine oil ages during use, it will start to become thinner and collect dirt and debris.

Your oil filter will trap most of that dirt and debris, but oil filters can only hold so much gunk before it doesn’t work anymore.

How to Fix It

This issue is an easy one to remedy. You just need to take your car to a local oil change location or buy the oil and filter to change your own oil. If you have a build-up inside your engine, you can also use a pour-in solution that will help remove the gunk inside your engine before you change the oil and filter.

#6 – You Have High Oil Pressure Inside Your Engine

Your engine is designed to have a selected range of oil pressure. If you have higher pressure inside the engine, it can push oil passed gaskets and seals that would normally prevent oil consumption. Adding too much oil during an oil change can also increase the engine oil pressure beyond recommended limits.

How to Fix It

If the issue is too much oil in the engine, you can drain out a small amount to decrease the volume to the recommended level.

If your oil pressure is too high because of another reason, you need to determine why.

#7 – You Have Worn Intake Valve Seals In The Cylinder Heads

The cylinder head or heads on your engine have valves that open and close to let air-fuel mixture into the combustion chambers.

The mechanical rocker arms or the camshaft that moves those valves open and closed require oil to stay lubricated. The valves have small seals that prevent the oil from entering the combustion chamber, but over time those seals can develop cracks that leak oil into the combustion chamber.

How to Fix It

The valve seals aren’t rebuildable or repairable. They should be replaced with a new set. Typically, only one or two seals out of the complete set develop cracks, but it’s a large job to remove the rocker arms or camshaft to replace one seal.

It’s best to replace all of them at one time and not worry that another one will develop a leak soon.

#8 – You Have a Vacuum Leak Or Blocked Crankcase Vent

Your engine requires vacuum to run accessories, but a vacuum leak can pull oil into the intake manifold. Your engine also creates pressure as the crankshaft turns, and that pressure needs to vent into the intake manifold. Both of these pressures, whether positive or negative, can cause oil to be collected in the intake manifold that will end up in the combustion chamber.

This will cause higher oil consumption and may foul your spark plugs or damage your catalytic converters.

How to Fix It

Vacuum leaks or a blocked crankcase vent can be hard to diagnose.

There are smoke machines that you can buy to inject smoke vapor into the engine and vacuum lines to trace a leak. The vacuum and crankcase vent lines are usually plastic or rubber and cheap to replace once you find the leak.

#9 – Your Driving Style Is Hard On The Engine

Believe it or not, your driving style can cause higher oil consumption.

If you lug the engine by working the engine harder at low RPMs, such as trying to pass on the highway without downshifting, it can cause higher oil consumption. You can also cause problems by repeatedly running your engine at high RPMs. It burns more oil, not to mention more fuel.

How to Fix It

This fix is pretty easy, and it doesn’t require expensive repairs by a professional or a large toolbox. You just need to change how you drive your car.

Don’t redline it repeatedly. Don’t drive around in high gear and try to make the engine perform.

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