Lawn Mower Is Burning Oil – 5 Causes & How To Fix

Front view of a lawn mower on a well-kept lawn, possibly experiencing issues like burning oil.

A lawnmower typically consumes up to 1 ounce of oil per hour.

If the lawnmower consumes more than this, you need to check your engine. Also, consider the oil that you are using.

Oil is important in petrol lawnmowers for engine lubrication, cooling, and preventing rusting of engine parts.

You might notice the smell of burning oil from the exhaust gases of your lawn mowers. In that case, your mower is burning oil. When your lawnmower is burning oil, here are 5 causes & how to fix them.

Lawnmowers are essential in ensuring the general cleanliness and orderliness of our lawns.

We should always be in the forefront to note any funny behavior it may have while in use.

What Is The Cause Of My Lawn Mower Burning Oil?

1. The Crankcase Is Overfilled

If the crankcase is overfilled, it can easily make the lawnmower burn oil. The carburetor float may have also shut off the solenoid. This is what easily allows gas into the engine, overfilling the engine oil in the lawnmower. This makes it malfunction and burn oil leading to smoke.

Solve this problem by draining oil from the engine to the recommended oil level.

2. Worn Piston Rings

The lawnmower engine can easily burn its oil if the piston rings are worn out.

This is the most common cause of petrol lawnmowers burning oil. Piston rings keep oil in the engine crankcase from entering the ignition chamber. When the oil passes through the narrow gap in the worn piston rings, it burns in the ignition chamber. It can also be disastrous if the valve seats are also worn out. Also, if the oil is lightweight, it can make the lawnmower burn it.

A faulty seat or fuel shutoff solenoid can easily stick open and allow gas to flood into the crankcase and overfill it, thins the oil, and makes it burn easily.

3. Low Oil Capacity

Oil can also start being burnt if the oil capacity has started reducing. This is because of reduced lubrication in the crankcase that makes the temperature increase inside the engine. Once the heat starts to heat up, it will start burning oil fast. The heat makes it start using more oil to keep the inner parts lubricated.

Once the oil ends, the engine will continue heating up and even blow out a valve or seal.

This will require to be fixed first before you use the mower again.

4. The Viscosity Of The Oil

Increased oil consumption can be caused by the wrong oil viscosity grade. The different lawnmower manufacturers have different specifications on the kind of oil you should use. Thus, trust their instructions to prevent any damage from occurring.

This will help to reduce the burning of oil or the lawnmower being slow.

5. Old Oil Or Leaks

You need to change the oil frequently. This is mostly if you stay for long periods without using your lawnmower. For push mowers, you need to change the oil every 25 hours, and for riding lawnmowers after 50 hours. In each season, always make sure to change the oil.

If the oil remains in the machine during the cold season, the lubricating components can easily break down and lose their efficacy which can cause the engine to heat up and burn through more oil during its next use. Also, frequently check for any kind of oil leaks. These leaks mainly cause white or dark smoke.

Always check around the base of the engine, oil tube, and tank.

Man performing maintenance on a lawn mower, possibly due to it burning oil, in a garden.

What Can I Do To Fix This?

1. Change Oil

You can drain all the oil that is there and put new recommended oil. This will help reduce the lawnmower from burning oil and making it smoky. Also, always check the capacity in the machine to know if you need to add more or reduce. This is a measure that you should always have in mind.

2. Lubrication Of The Engine

Just the same way, you need to lubricate your car engine frequently; you also need to lubricate the lawn mower’s engine more often. This will ensure its proper functioning. In all machines, lubrication is essential, and if you ignore this, it won’t function well.

3. Use The Recommended Oil For The Lawnmower

When you buy a lawnmower, enquire about the right oil you need to use for the mower. If you use the wrong oil for the mower, it can easily affect the functionality of the machine and make work harder for you. You should also follow all the instructions given to ensure that you don’t miss a step or perform the wrong use with the machine.

4. Maintain The Mower

Regularly clean the mower and check all the inner parts and external parts of the mower. The mower may be old, and you need to replace some parts. Thus, it is essential to replace the parts and fix them. This will help the mower to remain good and reduce the chances of the oil being burnt because of worn-out parts.

5. Enough Oil

Put enough oil in the lawnmower, not too much oil and not too little oil. It needs to be the right amount to ensure all is well. For this, read the user manual to know how much it needs or 100% efficiency.

6. Use Clean Fuel

Use petrol fuel from reputable sources in your lawnmower. Dirty petrol fuel may contain oil in it and cause you to think that the lawnmower has other problems. Good quality fuel keeps your lawnmower engine running properly with no problems. It also makes the lawnmower operate with the optimum power output. Additionally, prepare the proper petrol-oil fuel mixtures at correct petrol: oil ratios.

Improper mixing ratios may result in too much oil in the fuel-oil mixture. This causes your lawnmower to run with stoppages, overheating, and at a reduced power output.


Burning oil can cause smoke, and you need to take the proper measures to ensure all is well. Consult the owner’s manual of your lawnmower for instructions about the type and amount of oil to use in your unit. Black smoke is mostly produced when the fuel and air mixture is high, which makes combustion to be incomplete, and the unburnt fuel turns to smoke.

If that happens in your lawnmower, be assured that it has a dirty air filter. For this, just clean the filter or replace it with a good one, you may also have to adjust the carburetor. White smoke always shows that the engine is burning oil or has an overfilled crankcase. However, when it produces white or blue smoke, it means the oil has a pathway into the combustion chamber through worn-out seals.

You may need to seek professional help in some cases when your lawnmower is burning oil.

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