Your riding lawn mower will give you years of dependable service if you maintain the mower properly. A big part of any lawn mower maintenance program is changing the oil. Most manufacturers recommend changing your lawn mower's motor oil every 50 hours. Refer to your owner's manual for specifics on oil filters and capacities for your mower. Oil filters and oil are available at hardware stores and major department stores with a home and garden section.
Move the riding lawn mower to a level area and park the mower. Open the mower hood and allow the engine to cool so that the motor is warm to the touch.
Clean the area around the oil dipstick and fill tube with a clean shop rag. Remove any grass clippings and sediment so that no foreign matter gets into the fill tube. Pull the oil dipstick out of the filler tube and set it on a clean surface.
Place a drain pan under the oil drain valve. Most riding lawn mower drain valves are on the right side near the pedal. The drain valve will most often have a yellow cap or the same color cap as the top of the oil dipstick.
Twist the drain valve cap off by turning the cap counterclockwise and remove the cap from the drain valve. Allow the oil to drain completely into the drain pan. Some mowers will have a separate drain tube that connects to the end of the drain valve over a nipple. After attaching the drain hose, you turn the drain valve to open the valve. To close the valve, you turn the valve clockwise. Place the cap back on the drain valve after draining the oil.
Place the drain pan under the area of the oil filter if your mower uses a filter. Twist the oil filter loose with an oil filter wrench. Once the filter is loose you can thread the filter off by hand and remove the oil filter from the mower.
Apply a thin film of oil from the drain pan to the rubber gasket on the new oil filter. To apply the oil film, stick your fingertip into the old oil and rub the oil from your fingertip over the gasket. Insert the oil filter into the mower and thread the filter until the gasket makes contact with the base. Tighten the filter a half turn after making contact.
Add SAE 30 motor oil to the engine through the oil fill tube. Check the oil level by setting the oil dipstick into the tube and pulling the dipstick out. Fill only to the full level on the dipstick.