Lawn Mower Burning Oil: Here Is What to Do!

Lawn mover smoking

It’s the weekend, the sun is up, and you are tending to your lawn and notice white or blue smoke coming from the lawn mower. It is a tell-tale sign that your engine is burning oil. If you are new to gardening, this will probably boost your heart rate as you will believe the end is near for your mower. However, there are a few solutions to the possible causes of the white smoke. These can be dealt with to have your mower back in tip-top shape.

Once you suspect that your lawn mower is burning oil, check the engine and all its components as early as possible and repair the damages as they may lead to bigger repair bills if left unchecked. The engine’s heat causes any leaking oil to burn. Hence, the gray or white smoke. A little white smoke when you start up your lawn mower is, however, normal.

Common causes of the burning of oil are blown head gaskets, oil leaks, too much oil in the crankcase, or clogged air filters. The solutions depend on proper troubleshooting of the problem and include options such as the repair of the carburetor, oil change, and replacement of piston rings.

So, what solutions work for what problems? And what troubleshoots should be done to find out the problem? Let’s have a look at the common problems, their specific solutions, and the good practices to keep your lawn mower in good shape for as long as possible.


Why Is Your Lawn Mower Burning Oil?

The possible reasons for oil-burning by lawn mowers include:

  • Improper lawn mower storage
  • Insufficient oil
  • The use of the wrong oil grades
  • Oil leaks
  • Too much oil in the engine crankcase
  • Blown head gaskets
  • Worn out piston rings


Improper Storage

Depending on your residence, storage space sometimes proves to be a premium asset. It is therefore not uncommon for owners to store lawn mowers on their sides when not using them. Some owners also place them on their sides for maintenance or oil-changing. If you store or undertake repairs with your mower on the side, make sure to do the following to avoid problems caused by that:

  1. Drain the gas and oil before storing the mower. Leaving some parts of the lawn mower to sit in oil or gas for extended periods could easily damage your engine.
  2. When making repairs or doing maintenance, check the position of spark plugs to ensure they face upward and avoid leaks from the crankcase.


Insufficient Oil

As the lawn mower’s engine uses oil, temperatures begin to rise in the crankcase. This results in more oil burning, thus further reducing the oil levels in the crankcase. The drop in oil levels goes further and causes more oil to be used due to the increased friction.

To tackle this issue, ensure you monitor and maintain the oil levels as defined by the lawn mower’s instruction manual. Regularly keeping the oil at the right level prevents wear and tear on the engine. Just like with your car, insufficient oil in your lawn mower can damage the engine.


Wrong Oil Grade

Not all lawn mowers run on the same oil grade. You may think that using a different oil grade could increase efficiency, but it causes more harm than good. Indeed, the wrong viscosity of the oil will result in your lawn mower running too slow, and using the wrong weight of oil may damage your engine as lighter oil grades will burn more quickly.


Oil Leaks

Leaked oil easily burns due to engine heat. This combustion worsens the leaks as broken seals and damaged gaskets are more damaged. Regular maintenance is essential to avoid piling up the damages and increased repair costs later on. This maintenance involves:

  • Checking piston rings regularly for wear and tear. Oil leaks from even the smallest gaps easily grow into damages to the lawn mower’s engine.
  • Replace old oil after every season or 50 hours of service.
  • At the end of the season, don’t put away the lawn mower with oil and gas in it. Old oil causes the gaskets and seals to deteriorate and rot, resulting in a repair bill at the start of the next season.


Too Much Oil in the Crankcase

The most common technology in lawn mowers to monitor the gas flow into the engine is a solenoid. The carburetor has a float in it that connects to a solenoid regulating fuel flow to the engine. If the carburetor is damaged and the float gets stuck, the fuel shut off will be prevented. This results in too much gas being let into the engine, thus thinning the oil. The thin oil then burns much more quickly, generating white smoke.

If you overfill the crankcase, you may damage the carburetor. The solution for an overfilled crankcase is to drain the oil and refill it with new oil, paying attention to the manufacturer’s guidelines indicating the proper amount and type of oil.


Blown Head Gaskets

A head gasket helps the internal combustion process run properly and efficiently by sealing the engine block. Head gaskets also serve to keep oil and coolant from combining in the engine. If you have a blown head gasket, you’ll notice:

  • A sudden power reduction;
  • Smoke emanating from the engine;
  • The engine tending to overheat;
  • The lawn mower running rougher than usual.

Usually, if you notice a blown head gasket, it costs less and is easier to replace than attempting to repair it. Although fixing a blown head gasket is not difficult in theory, you’ll have to take out and put back together several parts for a successful repair.


Worn Out Piston Rings

As a lawn mower approaches its final service hours in the life cycle, the cylinders become sort of egg-shaped instead of perfectly round, as they were when new. Therefore, the piston rings wear unevenly, which results in poor seals. The engine will lose compression and crankcase pressure will build up, forcing oil up and out the crankcase. This results in oil-burning.



An additional often overlooked cause of smoke in lawn mowers is the carburetor’s need to be cleaned or adjusted. Thus, regularly check for carburetor defects, such as corrosion and dirt. Cleaning can easily rid the dirt but corrosion points at more trouble. Even after the cleaning, corrosion clogs the jets and tiny orifices, restricting the gas flow, resulting in more oil getting burnt.


How to Take Care of Your Lawn Mower?

Lawn mowers get less corrective attention than cars whenever they have faults or don’t start on the first try. Often, if a mower doesn’t start, we’ll yank and yank until the machine coughs up to life, repeating the same routine week after week, believing that’s how lawn mowers work.

However, just like a car, machines with smaller engines need regular maintenance to keep running for years. Below are some care practices for your lawn mower to ensure it works efficiently and maintains or extends its lifespan.


Carburetor Repair

Inspect the carburetor regularly for dirt and corrosion. If you don’t notice any corrosion on a carburetor, you can choose to rebuild rather than replace it. However, before doing this, remember that rebuilding isn’t always cheaper than repairing, nor does it assure to fix the problem. In some cases, you can buy a new carburetor for less than the cost of a rebuild, including the replenishment of chemicals.


  1. Dissect on a clean workbench. Start the disassembly from the bottom up (bowl, float, needle, seat, etc.), keeping all items together for easy reassembly. Make sure to take photos for easy, efficient, and assured reassembly.
  2. Match the new gaskets and O-rings with the old ones.
  3. Clean the different pieces of the carburetor. Rinse with water and blow dry them with compressed air afterward.
  4. Reassemble the carburetor’s parts and mount them back on the engine.
  5. Follow the manufacturer’s guide for adjusting idle speed and mixtures.
  6. Fire up the engine and enjoy the smokeless emission.


Air Filter Cleaning/Repair

Dirty air filters burn gas less efficiently and put a strain on the engine. Depending on your lawn mower’s mode, your filter could be paper (replaceable) or foam (cleanable). Paper filters are cheap and should be replaced yearly or whenever a clog up is noticed. Foam filters, on the other hand, need to be changed once or twice a season.


Checking and Changing Oil

Make sure to check your oil levels at least twice a season. Doing so in lawn mowers is the same as in cars. Twist off the (usually yellow) oil cap and clean the dipstick. Put it back in and make sure to twist it completely back in. Take it out once again, this time remembering to note the oil level and color. Healthy oil should be sort of golden brown and free of sediment rather than black and chunky. Black oil indicates the oil is up for a change.

Different lawn mowers have different locations for the oil drain plug (when they have actual oil drain plugs). Users’ manuals are a handy means to locate the specific model’s location for the plug. If there is no plug, you may have to tip over the mower and drain the oil to the selected container. Once emptied, fill up the oil reservoir and make sure to reach the right levels.


Clean Your Deck

An often overlooked task when handling lawn mowers is the cleaning of decks. The best time to clean the deck is right after mowing. To do so, tip the lawn mower with the air filter side up to ensure no fluids leak into it and damaging it. Use a brush or broom to clear out grass and a gloved hand for the chunky deposits. Feel free to use soap, water, and a brush to ensure the cleanest possible deck.


Replace Spark Plugs as Needed

Since a spark plug is a cheap and easy replacement, some folks do it annually. However, as long as your lawn mower starts well, replacing it every 2-3 years is perfectly fine. These pieces of equipment’s robust structure means they can even be used for much longer without needing to be changed, with replacements helping maintain peak performance.



The way you store your lawn mower affects its ability to start on the first try the following season. Thus, ensure a hassle-free startup after a long winter or session of no use by doing the following:

  1. Drain or empty the gas. Over months of no use, the gas turns murky and clogs up, which makes it difficult to start the engine. Luckily, there are options to help, including siphoning and using the gas in your car, or draining and disposing of following local hazardous waste disposal means.
  2. Disconnect the spark plug and clean it up. Dirt collected over time renders the spark plug less efficient at its operation.
  3. Remove and sharpen the blade. Branches, rocks, mulch, and natural dulling pile up over a mowing season. Therefore, it is essential to sharpen the blades. You can do either this on your own or by unmounting the blade and taking it to a hardware store.


Repair or Replace?

With many lawn mowers boasting a lifespan of about a decade, at some point, a consideration usually comes into play as to whether repair or replace the lawn mower. Hiccups that weren’t previously encountered, such as start-up issues and burning of oil, are signs that years are catching up. Once you start having problems after years of reliable service, consider how many years you have owned your mower.

Another aspect you should consider is the condition of your lawn mower. Sometimes, a few-year-old lawn mower is already calling for a replacement. Repairs may at times not be worth the cost and acquiring a new device may serve better both your pocket and lawn.

Years of experience working with your lawn mowers could have instilled reliable repairs and maintenance skills, but some levels of damages defeat the cost of repairing. Issues such as hitting a tree stump or rock and bending a power transmission shaft could cost up to a few hundred dollars in repairs. Chances are the damages may even completely stop the functionality of the lawn mower. At this point, a replacement is a much better option.


Lawn Mower Replacement Considerations

When worst comes to worst and repairs do not improve the state of your lawn mower, a replacement has to be considered if you are not going to outsource your landscaping. Some important considerations to ensure you buy the best lawn mower for your needs include the following.



Comfort is an important factor, as you are going to be walking or riding your new mower for multiple years. Simple things to ensure ease when mowing include the walk-behind mower’s adjustability for your height or the tractor seat’s firmness.


The Size of Your Yard

If you are tackling a small, flat space, a non-motorized mower is a better option. On top of being light, a non-motorized mower is cheaper, features fewer mechanical parts that may wear out, and is usually easier to maneuver.

For large tracts, a self-propelled mower offers better effectiveness. Consider mowers with variable speeds to ensure you can match your mowing speed to the lawn conditions and your walking speed.


Your Performance Needs

With most walk-behind mowers ranging from 140 to 190 cc, pick an engine size that will handle your need with ease, chomping through tall and wet grass, mulching, or bagging chopping away.


Power Supply

In a bid to escape the oil-burning and gas leaks, consider an electric and corded mower. These offer unlimited runtime compared to cordless electric mowers, while still being quiet, clean, and easy to start. Although, a minor inconvenience to consider is the cord itself, as some people are displeased with the cord running behind them.


Local Dealer Support

When getting machinery such as lawn mowers, gardening tools, and other small machinery, try and make purchases from a local area dealer, as this ensures you can get warranty and maintenance support, parts, and easy-access consultancy. The rapport created also ensures you can enjoy good deals later on for other purchases.

Like every other machine, lawn mowers feature different parts that require regular maintenance to improve and maximize the devices’ strength and performance. The tips and advice shared above cover the major aspects of keeping the machine in tip-top shape.

However, if troubleshooting and repairs do not correct the problems encountered, reach out to a professional and incur a small expense rather than simply brute forcing operation and causing further damages. A yearly service by a professional for the much more complex mowers is advised to ensure minimal maintenance costs.

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