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Lawn Mower Maintenance

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Change Lawn Mower Oil
Someone changing oil in a lawn mower.

To ensure it performs up to its maximum capacity, make sure you change lawn mower oil at regular intervals. Old oil that is black or contains debris should be drained and replaced. This will improve performance, reduce costly repairs and extend engine life of gas lawn mowers. A push mower has an oil capacity of 15 to 18 ounces. It should be changed either every 50 hours or annually, whichever comes first. A riding mower has an oil capacity of 48 to 64 ounces. It should be changed either every 100 hours or annually, whichever comes first.

  • Before changing the oil in the lawn mower, disconnect the spark plug.
  • Remove the drain plug underneath the mower and allow it to drain into an oil-safe container.
  • If the mower does not have a drain plug, use an oil extractor kit to remove oil from the compartment. 
  • Add new small engine oil to the compartment up to the dipstick fill line. Oil formulated for small engines will keep your mower running at its best.
  • Be sure to recycle the old oil properly.
Clean or Replace Your Air Filter
Someone changing the filter in a lawn mower.

A lawn mower’s air filter should be cleaned or replaced to keep dirt and debris from clogging the engine.

  • Determine if you have paper or foam air filters.
  • Check your operator’s manual to determine if air filter pre-cleaner is required. If so, follow the instructions in the manual.
  • Disconnect the spark plugs before removing filters.
  • Replace paper filters when they look dirty. You should keep a few on hand. 
  • Plastic foam filters should be removed and washed with warm, soapy water. Air-dry thoroughly, then work about 2 tablespoons of clean mower oil evenly across the filter to lightly coat it.
  • Reinstall the filter according to instructions.
  • Reconnect the spark plugs.

Tip: Be sure to check the air filter a few times during the mowing season, particularly if the mower is getting heavy usage.

Treat Your Fuel
Someone pouring fuel cleaner in a lawn mower engine.

Gasoline can go stale in as little as 30 days, so avoid using stale gas in your lawnmower. Add a fluid stabilizer and treatment to keep gas fresh and protect your mower’s engine. Most lawn mower tune-up kits contain fuel stabilizer as well as spark plugs and air filters.

Tip: If gasoline has been stored in a fuel container all winter, do not use it in your lawn mower.

Blade Maintenance
Someone sharpening a lawn mower blade.

Between regular use and potential damage from unseen branches or rocks, mower blades endure a great deal of stress. A dull mower blade cuts unevenly and shreds the tips of grass blades, which can turn them brown and make the lawn look dry. The ragged ends can also be entry points for disease.

  • Brush off the mower after each use to keep debris from collecting on the blades.
  • Sharpen the blade regularly. Remove the spark plug and then remove the blade from then lawn mower.
  • You can sharpen the blade by hand with a file or grindstone, keeping the blade at a 45-degree angle.
  • Alternately, you can sharpen the blade with a bench grinder. Be sure to wear eye protection.
Change the Spark Plug Annually
Someone changing a spark plug.

Replace lawn mower spark plugs once a year, such as at the beginning of mowing season.

  • Disconnect the spark plug wire and then remove the existing spark plug with a wrench or pliers. 
  • To ensure you purchase the right replacement plug, write down the code on your existing plug, consult your mower’s owner’s manual or just take the old plug with you when you go to purchase a new one. 
  • Screw in the new plug and reconnect the spark plug wire.
How to Clean a Lawn Mower
Someone cleaning around the blade of a mower.

A couple of times a year, give the mower a good cleaning. 

  • With the gas tank empty, turn the mower on its side. 
  • Remove any debris that may be wrapped around the blade or caked up on the underside of the mower deck. 
  • Spray the underside of the mower deck with a garden hose to loosen dirt and dried-on grass. 
  • Scrub the deck with a soft brush and soapy water. Then rinse off with a hose.
  • Dry the mower thoroughly before storing.
How to Winterize a Mower
A lawn mower stored in a shed.

After your last mow at the end of the growing season, run until it is out of gas to empty the tank.

  • Leave the gas tank empty until spring. 
  • With the gas tank empty, remove the oil fill cap (if applicable) and turn the mower over to drain the engine oil into a suitable container for recycling. 
  • If your mower has an oil drain plug, use that instead of turning the mower on its side. 
  • Refill the engine oil reservoir per your mower manufacturer’s recommendations and then replace the oil fill cap.
  • Store a mower in a dry, protected location such as a garden shed or garage. Never store it next to a water heater or furnace.

Tip: Some lawn mowers benefit from “fogging” the engine at the end of the season. This involves spraying a coating into the carburetor and spark plug housing to prevent water from entering over the winter.

Small Engine Oil Recommendations
A chart showing different engine oil types.

Different oil types are more effective in different climates depending on the temperatures. Learn which one will be best for your mower.

  • SAE 30 is best for warmer temperatures and is the most common oil for small engines.
  • SAE 10W-30 is suitable for a varying temperature range. This grade of oil improves cold weather starting, but may increase oil consumption.
  • Synthetic SAE 5W-30 offers the best protection at all temperatures as well as improved starting with less oil consumption.
  • SAE 5W-30 is formulated for very cold temperatures.
  • Vanguard 15W-50 is suitable for a varying temperature range and for continuous use, such as commercial lawn cutting applications.

Tip: When choosing lawn mower oil, use a high-quality detergent oil classified as “For Service SF, SG, SH, SJ” or higher. Do not use special additives. Synthetic oils are an acceptable oil at all temperatures. Use of synthetic oil does not alter required oil change intervals.

Lawn Mower Maintenance Tips
Woman cutting grass on a riding lawn mower.

Consider these additional tips for lawn mower maintenance.

  • The lawn mower’s motion and engine vibrations can cause such hardware as the fasteners and wheels to loosen. Periodically check them and tighten as needed.
  • If you have an electric mower, be sure to inspect the cord or battery to make sure they remain in good condition.
  • Store the battery or cords in a dry location.
  • If you have a riding lawn mower, replace the fuel filter once a year and make sure the tires are properly inflated. 
  • If the wheels are damaged, swap them out with replacement wheels.
  • Before mowing, clear your yard of visible rocks and other items that could damage the mower.
  • Mow a dry lawn to keep deck from getting clogged with damp clippings.
  • If your blade has dents or cracks, replace it. Blades that are damaged won’t respond to lawn mower blade sharpening and will only cause more damage to your lawn. 
  • Most maintenance tasks are easy, but if you’re busy you can seek a professional tune-up from a lawn mower repair service.

Sharp blades and a well-cared-for engine will mean your mower keeps humming for years to come. Always review your owner’s manual for detailed instructions specific to your engine model. Consistent lawn mower maintenance throughout the year will ensure your equipment will last and your yard will look its best.

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