One of the things that you always want to keep an eye on while using anything with a gas powered engine is the oil consumption. In a Craftsman lawnmower, the engine gets very hot and the oil can degrade over time. If the engine does not have the proper amount of oil, the parts will wear. Eventually, the lawn mower engine will get stuck in one position, or freeze and you will have to buy a new one. Changing the oil is a simple maintenance task that you will find pretty simple.
Disconnect the spark plug usually found at the front of the lawn mower. You do not want to take any chance of the mower starting while you are changing the oil. Work on a flat area and throw down some newspaper if you are concerned about spilling any oil. Only change the oil when the engine is totally cool or you run the risk of burning yourself.
Locate the oil drain plug at the base of your Craftsman lawn mower engine. It is usually under the mower and can be opened by turning the bolt. Make sure you open the oil cap on top to allow the oil to drain freely. If you cannot find a plug, you can always tip the lawn mower over and simply pour the oil out of the same spout you pour the oil into.
Be careful to have your oil collection pan ready. You won't be able to get all of the oil out, but it will be enough.
Put the plug back on when the oil stops dripping and set the mower upright on the flat ground. Pour the new oil into the opened oil reservoir. Check with your owner's manual to be sure of the type. Start with just about 10 ounces and then check the level with the dipstick. You do not want to overfill it or you can actually damage parts of the mower. Add a couple more ounces if the stick still reads low until you get it into the full range.
Clean up any oil you spilled with disposable rags. Twist the oil cover back on, making sure it is snug. Set the spark plug back in place. Prime the engine for about nine pushes and then start it. It should run smoothly after just one or two pulls if it is tuned properly. Plan on changing the oil once a season to keep your mower in good condition, but check the oil level every five hours of use.