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Lawnmower Is Burning Oil: 6 Reasons And How To Fix

A lawnmower in your garden is quintessential. It helps trim grass to an even and appropriate height and keeps weeds in check.

Typically, a lawnmower can use up to 1 ounce of oil per cylinder in an hour. That’s already massive.

However, it could burn more under problematic circumstances. When this happens, your lawnmower is burning oil.

The situation could arise from a problem with the engine or the oil. If you are experiencing such a technical issue on your lawnmower, we got some answers.

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Causes of A Riding Mower Burning Oil

Cases of lawnmowers burning oil are not uncommon. These reasons range from improper storage to an overfilled crankcase.

1. An Overfilled Crankcase

When your lawn mower’s crankcase gets overfilled, it starts to burn oil. How does this happen?

Your lawn mower’s engine contains a piece of electromagnetic equipment called a solenoid. It is responsible for monitoring the gas flow into the engine.

The float in the carburetor connects to the solenoid. If the carburetor malfunctions or gets stuck, it prevents fuel shut off.

The result is an overflow of gas into the engine, which thins the oil.

Consequently, oil burning occurs much faster, leading to the mower producing a cloud of white smoke.

You can fix the problem by checking the carburetor and repairing it. As a precaution, always use the manufacturer’s manual to check what oil grade is best for the machine and use only it.

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2. Piston Rings Are Worn Out

The piston rings of your lawnmower wearing out is a potential cause for your lawnmower burning oil.

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As a result of the wear and tear of the pistons, oil flows through the narrow gap between the cylinder wall and the piston, burning in the ignition chamber.

This leads to a significant drop in fuel efficiency as, in normal circumstances, the oil goes through the usual 2/4 stroke combustion.

Burning of oil also occurs when the valve seats wear out. Replace any worn-out parts in your lawnmower to overcome this problem. 

3. Using The Wrong Oil Grade

Different lawn mowers use different oil types. Using the wrong oil grade on your lawnmower could cause it to burn oil, decreasing the fuel efficiency.

Another important parameter associated with oil is viscosity. Oil with the wrong viscosity causes the lawnmower to slow down, increasing your operational cost.

Low-grade oil could also damage the lawnmower engine.

You also want to check the owner’s manual to know whether your lawnmower is meant for a lighter or heavier oil.

Using lighter oil on a heavy oil engine makes the oil burn more quickly. 

4. Low Oil Levels In The Crankcase

A decrease of fuel in the crankcase below appropriate levels is also a cause for your lawnmower burning oil.

Insufficient oil causes temperatures to increase inside the crankcase due to more friction.

Oil gets burned up faster due to higher temperatures and a lack of lubrication inside the engine. A valve or a seal in the engine could also blow up.

Take care of low oil levels in the fuel tank by routinely filling it up to the correct levels. This helps prevent wear and tear and repair costs in the future.

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5. Oil Leaks

Your lawn mower could also burn oil because of oil leaks in the engine or the lubricating system.

Usually, such leaks are rarely visible, and it might take some extra checks to spot them.

Common areas the oil leaks occur include the oil gaskets, the breather cavity, and the O-ring. A tell-tale sign of an oil leak is your lawnmower emitting dark or white smoke.

Another sign of an oil leak in your mower is sluggishness or sputtering during operation.

If this happens, do check the piston rings or seals. Do a thorough inspection of your lawnmower, especially at the oil tank, the engine base, and the oil fill tube, for any leaks.

Here are some measures you can take to prevent oil leaks from happening:

  • Avoid storing your lawnmower for long periods with gas and oil inside. Old oil causes the seal and gaskets to wear, making you incur the repair cost the next time you want to use it. 
  • Regularly check and replace any worn-out parts.
  • Replace old oil with new oil after every 25 hours of use. 

6. Storing Your Lawnmower On One Side

We hope your garage is spacious enough to store your lawnmower. However, avoid keeping it on one side if it isn’t the case.

Gardeners are also guilty of turning it on one side while replacing old oil or doing maintenance. Doing this is a potential cause for your lawnmower burning oil.

Here is what you should do to avoid this eventuality. 

  • Keep your spark plugs facing upwards when doing maintenance. It helps to avoid leaks from the crankcase. 
  • Drain oil or gas from your lawnmower before keeping it away.
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How To Know When Your Lawn Mower Is Burning Oil?

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Having said it all, a common sign of your lawnmower burning oil is the production of white smoke.

Often, you will also spot the production of black smoke. A high fuel to air ratio results in incomplete combustion that makes the unburnt fuel come out as black smoke.

If this is happening, check for a dirty air filter in your lawnmower— clean it up or replace it with a better one.

There are also cases of your lawnmower producing blue smoke. This happens when oil finds a pathway to the combustion chamber via worn-out seals.

Conclusion

Lawnmowers are efficient machines for trimming grass and unwanted plants in your lawn or garden. Sometimes, they may develop mechanical issues commonly noted by the production of black or white smoke.

The output of white smoke is a clear indicator of your lawnmower burning oil. Should this happen, you already have a troubleshooting guide above at your disposal.

We have outlined all the possible reasons and the corresponding solutions.

Lawnmower Is Burning Oil: 6 Reasons And How To Fix

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