Gasoline powered push mowers are often neglected until they break down. Just like your car, your lawn mower should get a tune-up before the start of the mowing season. Learn how to do so, and the mower will last you for many seasons. A complete lawn mower tune-up will only take an hour to perform once you have your parts. Mower tune-up parts are available at most hardware stores.
Disconnect the spark plug wire boot from the spark plug by pulling the boot off with your fingers. Always disconnect the spark plug before performing any service on the mower.
Remove the screw that secures the air filter housing to the mower with a flathead screwdriver. Pull the air filter out of the housing. For mowers that use a paper air filter, replace the filter with a new one. Clean foam filters in a mild dish washing detergent and warm water, if your mower uses a foam filter. Rinse thoroughly and allow the filter to air dry before reinstalling in the housing.
Lift the up the side of the mower opposite the oil filler cap and rest the mower on its side. Wedge a board between the mower deck and the blade to prevent the blade from turning.
Remove the bolt that secures the blade to the mower with a socket wrench. Pull the blade off and inspect the blade for damage. Replace the blade with a new one if the blade has damage. Sharpen the blade with a file, if there is no damage. Reattach the blade to the lawn mower using the securing bolt.
Lower the mower back onto all four wheels and grab the small container. Raise the oil plug side of the mower and locate the oil drain plug. The drain plug will be next to the center shaft. Remove the bolt with a socket wrench and allow the oil to drain into the container.
Thread the bolt back into the oil drain hole after the oil has drained and tighten the bolt with the socket wrench. Set the mower back down and remove the oil fill plug at the top of the engine. Pour SAE 30 motor oil into the filler neck and reinstall the drain fill plug.
Remove the spark plug using a socket wrench. Thread a new spark plug into the engine by hand. Tighten the spark plug with a socket wrench. Push the spark plug boot back over the spark plug until it locks onto the plug.