Park the Cub Cadet zero turn mower on a level surface, and engage the parking brake. Turn off the mower, and remove the key from the ignition.
Wipe the area around the oil fill tube and the drain area with a rag. This helps prevent getting dirt and debris inside the engine. The oil tube has a yellow cap and is usually on the left side of the engine. The drain tube is usually on the right rear of the engine. Some models have a drain pipe that require a ½ inch hose adapter. Other models have a flexible drain tube. There is a hole in the base of the mower that the drain tube or adapter hose fits through.
Place a catch basin under the hole in the base of the mower. Remove the cap from the oil fill tube, and place it out of the way on a rag. If your unit uses a drain pipe, slide the adapter hose over the end of the pipe nipple. Feed the other end of the adapter hose through the hole in the base of the unit. If your mower uses the flexible line, insert the end of the line through the hole in the base.
Twist the drain pipe counterclockwise to drain the oil. If you have the flexible drain tube, unscrew the cap at the end of the tube to drain the oil. Replace the cap once the oil completely drains. Twist the drain pipe clockwise to close the drain and remove the adapter hose, if your mower uses the drain pipe.
Pour 2 quarts of SAE 20W-50 motor oil into the oil fill tube. Wipe the oil dipstick on the bottom of the fill cap with the rag. Insert the dipstick into the fill tube and pull it back out again. Check the oil level, and continue adding oil until the level is at the full mark on the dipstick. Place the dipstick inside the fill tube, and turn the cap clockwise.