The air filter needs to be clean and in good condition in order to stop dirt, dust, and debris from getting into the engine. It is recommended that you clean or change the air filter every 25 hours or once a season, whichever comes first. Pleated-paper air filters have to be replaced, they should not be cleaned and reused. Foam air filters can be cleaned with hot water and dish detergent then wrung dry and saturated with engine oil before reinstalling into the mower.
Fuel filters can be removed and cleaned of residue, however if there is debris clogging the mesh screen inside the filter it should be replaced. Some fuel filters are located in the fuel line and some are located inside the fuel tank.
The oil level in lawn mowers should be checked after 8 hours of use and changed every 50 hours of use or once every season. Fresh oil is a golden or amber color and as it gets old and used it will turn darker.
Before storing the lawn mower, spray a degreaser on greasy and dirty areas, let the degreaser sit for 10-15 minutes then wipe the sprayed area with a clean cloth. Rinse off the lawn mower with a hose and dry completely.
Use a small bristle brush to remove any debris from the cooling fins. In most cases the blower housing will need to be removed to access the cooling fins.
Lawn mowers require clean, fresh fuel for best performance from the engine. During the off season when your lawn mower is being stored the fuel should either be drained from the lawn mower or a fuel stabilizer should be added to prevent clogs in the carburetor.