Oil is a must-have for a lawn mower to function, and changing the oil is a basic maintenance task that should be performed regularly. Removing the old oil and installing new oil is not a difficult process and helps the mower run smoother. Follow the mower manufacturer's instructions for the specific grade of oil to use.
Type of Oil
You usually have no need to buy high-priced oil for your mower. SAE 30 motor oil is commonly recommended for use in a lawn mower engine, but the safest best is to use the type of oil your lawn mower manufacturer recommends. Often 10W-30 or 10W-40, the same motor oil types that are used in vehicles, can also be used in a lawn mower.
When to Change the Oil
The lawn mower's owner's manual will list the best intervals for regularly changing the oil. Often, this time frame begins after approximately 25 hours of usage. Change the oil even more frequently if you operate the mower in an extremely dusty environment. If you do not have the owner's manual, at least change the oil in the spring, around March, before the next mowing season begins. Changing the mower's oil before every other mowing season is the longest you should ever go between oil changes.
Removing the Gas and Spark Plug
Before you change the lawn mower's oil, the first steps you should take are emptying all the gasoline from the mower's fuel tank and disconnecting the spark plug wire. When you change the oil, you usually tilt the mower to one side, allowing the oil to drain out. Removing the gasoline first prevents the gas from spilling out. You can either simply run the mower to empty the gas tank, or siphon the gasoline out. Removing the connection between the mower's spark plug and the spark plug wire prevents the mower from accidentally starting while you are changing the oil.
Oil Change Considerations
Some mowers have an oil drain plug, which you can open to drain out the oil. If not, and you do tilt the mower to one side, ensure the carburetor is on the raised side of the mower. Running the mower between two and three minutes before you change the oil warms up the oil, allowing it to be less thick and easier to flow out. Spread newspaper on the ground to catch any drips that the oil pan misses.