How can I change the oil in a lawn mower that doesn't have a drain plug?

If your lawn mower doesn't have a drain plug, you can tilt it on its side to drain the oil. Make sure the oil is cool, remove the oil fill cap, and tilt the mower so the oil drains out through the oil fill hole. Be careful not to tilt it too much or oil may leak out of the air filter. Once the oil is drained, refill the mower with the appropriate amount of new oil.