All rear differentials in the 4WD models use API GL-4 (oil grade) which is SAE 80W-90 (viscosity).
See Figure 1
This rear differential applies to 4WD models only.
- With the vehicle parked on a level surface, remove the filler plug from the back of the differential.
The plug on the bottom is the drain plug.
- If the oil begins to trickle out of the hole, there is enough. Otherwise, carefully insert your finger (watch out for sharp threads) into the hole and check to see if the oil is up to the bottom edge of the filler hole.
- If not, add oil through the hole until the level is at the edge of the hole. Most gear oils come in a plastic squeeze bottle with a nozzle, making additions simple.
- Install the filler plug and drive the truck for a short distance. Stop the truck and check for leaks.
DRAIN & REFILL
To drain and fill the rear differential, proceed as follows:
- Park the vehicle on a level surface. Set the parking brake.
- Remove the filler (upper) plug. Place a container which is large enough to catch all of the differential oil, under the drain plug.
- Remove the drain (lower) plug and gasket, if so equipped. Allow all of the oil to drain into the container.
- Install the drain plug. Tighten it so that it will not leak, but do not overtighten.
- Refill with the proper grade and viscosity of axle lubricant. Be sure that the level reaches the bottom of the filler plug.
- Install the filler plug and check for leakage.