It is very important to change the oil on your lawn mower just as important as changing the oil in your car. The oil liberates, cools and cleans the engine. It is best to check your manufacturers information to know how often to change the oil. To change the oil you will need the following: a wrench, gloves, a drop cloth, a socket wrench, oil container, a brush, a new oil filter, an oil filter wrench and fresh oil. It is recommended that you read the information on your manufacturers' sheet before you start. Oil is easier to change when it is warm, so turn on the mower and let it run for a minute or two. Put mower on a drop cloth in a well-vented area. Clean up the mower by brushing off any old grass. Be careful you don't burn yourself, as the engine will still be hot. To be safe, remove the battery by always removing the black cable first and then the red. Find the oil fill cap and open it. Now open the cap on the drain valve. Slide the manufacturers' drain tube onto the valve. Push in the valve and turn counter clockwise, this will unlock the valve. Now pull tube and it will start draining into the container. When the oil is all drained; close the valve an recap. Now it is time to remove the oil filter with an oil filter wrench and add the new oil filter. Add the manufacturers' recommended oil. Never dispose of the oil in the drain. Call the recycling in your city and get instructions on recycling the oil. Wipe up any excess oil with a rag. Reconnect the battery starting with the positive cable and then the negative cable. Get on your mower and get to work, the grass needs cutting.