Allow the lawn mower to cool completely after mowing. Spray the top of mower with a garden hose to remove the grass clippings and debris. Lift the side of the mower and remove the grass buildup under the deck. Use the garden hose to spray away the grass and dirt especially around the mower blade shaft.
Remove the screw that secures the air cleaner housing to the mower with a flathead screwdriver. Pull the screw out and take the top off the housing. Pull the foam air filter out and clean the filter in warm soapy water. Rinse the filter out and squeeze the water out of the filter. Set the filter out in the sun and allow the filter to completely dry.
Place 2 tablespoons of clean motor oil on the filter and work the oil into the foam. Place the air filter back in the housing and reattach the cover. Secure the housing to the mower with the retaining screw.
Change the spark plug once a year. The spark plug is on the front of the mower engine. Pull the spark plug wire boot off the spark plug. Remove the spark plug from the engine with a socket wrench. Replace the spark plug with one that is the same capacity. Spark plugs are available at hardware stores. Thread the new spark plug into the engine and tighten with the socket wrench. Push the spark plug wire boot back over the spark plug.
Change the oil at the end of each mowing season. Drain the oil from the engine and fill with SAE 30 motor oil.
Sharpen the blades before the start of each mowing season. Sharp blades keep your lawn looking healthy. Remove the blade from the lawn mower shaft and sharpen the blade with a file. If the blade is bent or shows damage, purchase a replacement blade and install the blade on the mower.