Drain and replace transmission fluid at specified intervals, only after the engine has cooled. Purchase the required transmission fluid and a new filter. You'll need a floor jack, jackstands, a drain pan, newspapers and clean rags. Raise the vehicle, place the drain pan under the transmission pan and remove the drain plug. After fluid drains, reinstall the plug. Remove the pan mounting bolts, tap the pan with a rubber mallet, lower the pan and drain remaining fluid. Remove the filter and O-ring. Inspect and clean the pan and filter. Remove old gasket material, install a new O-ring and filter. Clean the gasket surface on the transmission pan, install the gasket and pan, and tighten the bolts. Check for leaks and fluid level when hot.