An essential step in extending the life of your mower is changing the oil. Disconnect the sparkplug wire before you start. Remove the oil plug and drain the oil into a safe container. Replace the plug without over-tightening. Check the owner’s manual for the recommended oil type. Fill the reservoir with oil, checking the level several times until the dipstick registers full. Replace the dipstick and reattach the sparkplug wire. And don't forget to dispose of the oil properly.