Run the mower for a few minutes to warm the oil
Turn off the engine and disconnect the spark plug wire
Place the mower on a level surface
Position an oil drain pan under the mower
Remove the oil fill cap or dipstick
Drain the old oil by tipping the mower carefully or opening the drain plug if equipped
Allow all oil to drain completely
Reinstall the drain plug if removed
Refill with the correct type and amount of new oil
Check the oil level with the dipstick
Add small amounts of oil if needed
Reinstall the oil fill cap or dipstick
Reconnect the spark plug wire
Start the mower and check for leaks
Dispose of used oil properly