Use only Premium gasoline. Each time you fillup the Gas Can, add 1 to 2 ounces of Fuel Stabilizer (like Star Tron Enzyme Fuel Treatment) to it. The Ethanol (Alcohol) that is currently added to gasoline is very corrosive and can damage lawn mower engine.
When finished using lawn mower, shut off fuel supply to carburetor by turning little white knob to 3 o’clock / horizontal position.
At end of season run lawn mower engine until lawn gas tank is dry. Shut off engine and fuel supply to carburetor.
Heating / Cooling System
Replace Air Filter every three months (four times a year), especially at the beginning of the heating and cooling seasons and then about midway through those seasons.