The rear differential on the 2002 Toyota Tacoma is the main gear box for the rear axles. Both rear axles attach to the inside of the rear differential. The rear differential is controlled by a drive shaft that is connected to the back of the transmission. When the truck is in gear and moving, the shaft on the back of the transmission turns the drive shaft. The drive shaft then turns the rear differential gears. The fluid inside of the rear differential is what keeps the gears cool and lubricated.
Park the 2002 Toyota Tacoma in a safe work environment with a flat surface.
Jack the rear of the 2002 Toyota Tacoma up and place the jack stands under the leaf spring connector plates on both sides of the truck. Then, lower the truck slowly onto the jack stands.
Locate the rear differential drain plug on the bottom of the rear differential housing. Slide the oil catch pan underneath the drain plug. Loosen and remove the drain plug with the 1/2-inch breaker bar and the 15/16-inch socket. Set the drain plug to the side. Once all of the fluid is drained out, insert the plug back in the drain hole and tighten down tight with the breaker bar and socket.
Locate the fill plug on the back of the rear differential. Loosen the fill plug with the 1/2-inch drive breaker bar and the 15/16-inch socket. Set the plug to the side.
Insert the tip of the 75-90 gear oil bottle into the fill hole and pour all of the gear oil into the rear differential. Make sure to pour all four quarts into the rear differential. By the time that you get the fourth quart almost emptied, the gear oil should be coming out of the fill hole.
Screw the fill plug back into the fill hole and tighten down with the breaker bar and socket. Remove the catch pan out from under the truck.
Jack the rear of the 2002 Toyota Tacoma back up and remove the jack stands. Lower the truck to the ground.
