Craftsman advises to change the oil in your riding lawn mower every 50 hours of operation or every season, whichever comes first. Clean oil is imperative to the engine operation to lubricate internal moving parts, carry worn metal away, lubricate seals and gaskets and to cool the engine. The process is the same for all Craftsman riding lawn mowers, including zero turn radius mowers and models with automatic transmissions.
Start your Craftsman riding mower and move it to a level clean area, such as a garage or driveway. Allow the lawn mower to idle for about 10 minutes. This warms and thins the oil so it drains easily. Turn the lawn mower off.
Lift the engine cover and walk to the right side of the engine. The right side is the side that is on the right as you sit on the mower.
Clean around the oil dipstick tube with a shop towel to prevent debris from entering the tube. Clean the area around the oil drain valve. On some models, the oil drain valve is on the bottom of the engine; on others, it's near the bottom of the engine on the right side and has a yellow cap.
Pull the yellow cap off the oil drain valve or remove the oil-drain plug, depending on your model mower. Place an oil drain pan or other container under the bottom of the loose end of the oil drain tube or drain plug. On models that include an oil drain tube, insert it onto the oil valve tip, push the valve inwards and pull it out to unlock it.
Allow the oil to drain until it no longer flows out..
Walk to the opposite side of the lawn mower. Place a small plastic disposable container underneath the oil filter. Place a pair of adjustable pliers on the oil filter, turn it counterclockwise and remove it. Dip your finger in fresh oil and apply it to the rubber seal of a new oil filter. Screw the new oil filter in place clockwise until it is hand-tight.
Press the yellow cap onto the drain valve to seal it or re-install the drain plug. Remove the oil drain tube if you have one, and lock the valve.
Insert a funnel into the dipstick tube and fill it with fresh oil a little at a time, checking the oil level on the dipstick until it is at the full level.
Start the lawn mower and let it run a few minutes to circulate oil into the oil filter. Re-check the oil level and add oil accordingly until it reaches the full level.