Regular maintenance will keep your lawn mower running smoothly and prolong its life. Cleaning the air filter at regular intervals, keeping the oil fresh, and using high-octane gas are a few simple practices that will pay off in the end. Also important is changing the sparkplugs at least once per season. The only tool required is a sparkplug wrench, or the proper-sized deep drive socket.
Search for the sparkplug; it's on the engine, usually on the right or left side. Look for a thick black rubber wire that ends in a rubber boot.
Remove the boot to reveal the sparkplug. Use pliers to pull the boot off if it is tightly in place.
Place the sparkplug wrench, or deep drive socket, over the sparkplug and turn counterclockwise to remove the plug.
Insert the new sparkplug. Tighten snugly, turning the wrench counterclockwise.
Push the rubber boot back into place.