Why is Your Vehicle Burning Oil?

October 27, 2018 @ 1:00 am

Why is Your Vehicle Burning Oil?

Your vehicle starts burning oil when the oil escapes from inside of the engine’s lubrication system and into the combustion chamber. This problem develops over time, as mileage on your car results in wear and tear on valves and other parts meant to keep oil sealed in tightly. 

How do I know if my engine is burning oil?

If your car or truck is burning oil, you will likely smell the oil burning as it hits the hot components of your engine. You will also notice bluish smoke being emitted from your exhaust pipe when the engine is running. Another way to tell if your vehicle is burning oil is by regularly checking your oil levels. If you notice you regularly need to refill your oil by a quart or more a week, it’s time to troubleshoot which component of your engine is allowing oil into the combustion chamber. It’s best not to put off the issue of your vehicle’s oil burning, as you can damage your engine if there’s not enough lubrication. The most common culprits that cause oil burning are clogged PCV valves, bad valve seals, worn valve guides, and worn piston rings.

PCV valves

There’s a strong chance that, if your vehicle is burning oil, your engine has a bad or clogged positive crankcase ventilation valve, or PCV valve. Luckily, if your PCV valves are clogged and need replacing, you can likely repair the problem easily and affordably. This small, simple repair will save you from possibly damaging your engine from low fluid levels and will decrease the amount of pollution your vehicle releases into the air.

When the engine is running, pistons go up and down, creating pressure in the block of the engine. If there’s no way for that pressure to be released, seals can blow and cause problems with your engine. The PCV valve serves the purpose of releasing combustion gases in a controlled manner from the crankcase of the engine; but as PCV valves age, they get clogged up and begin to suck oil along with crankcase gas into the engine, and consequently much of your vehicle’s oil burns off. 

Bad valve seals

Located in the cylinder head above the combustion chamber, valves allow pressurized oil to be pumped into the top of the head, lubricating the valveterian. The valves have seals to keep the oil from flowing into the combustion chamber, but once the seals wear out, you will notice your vehicle burning oil.

Worn valve guides

If you notice bluish smoke is emitted from your vehicle when you are decelerating or just starting your engine, worn valve guides are likely what’s causing your oil to burn. Valve guides in the cylinder head are intended to keep oil from leaking out, but as they age, a gap forms that allows oil to flow down the valve stem into the combustion chamber.  

Worn Piston Rings

If your engine’s piston rings are worn out, they are no longer able to provide vital lubrication to the cylinder walls nor seal the combustion chamber. Pressure from combustion reverses, causing oil to ultimately end up being burned.

Prevent your engine from burning oil 

Read your owner’s manual to make sure you understand how often you need to check valves and piston rings in your vehicle. Cleaning or changing your PCV valve every once in a while, about every three years, is one way you can prevent the problem of your engine starting to burn oil. You can remove the PCV valve and clean any debris with carburetor spray cleaner, but it may be better to simply let your favorite auto shop replace this valve every three years. There are nylon parts inside that can warp from heat and it’s an inexpensive part vital in preventing engine problems. Taking your car into your auto shop to be examined regularly will also help you ensure that your valves and piston rings are all in good shape.