- Use multipurpose gear oil API GL4 or GL5 SAE 75W90 gear oil in the transfer case. Check your Owner's Manual under Specifications for any late changes that may apply to your specific vehicle.
The oil in the transfer case should be checked at least every 7,500 miles (12,000 km) and replaced every 25,00030,000 miles (40,00048,000 km), even more frequently if driven in deep water.
- With the truck parked on a level surface, remove the filler plug from the side of the transfer housing.
- If the lubricant begins to trickle out of the hole, there is enough. Otherwise, carefully insert a finger and check to see if the oil is up to the edge of the hole.
- If not, add oil through the hole until the level is at the edge of the hole. Most gear lubricants come in a plastic squeeze bottle with a nozzle; making additions simple.
- Install the filler plug and gasket, then run the engine and check for leaks.
DRAIN AND REFILL
- The transfer case oil should be hot before it is drained. If the engine is at normal operating temperature, the oil should be hot enough.
- Raise and safely support the truck using safety stands.
- The drain plug is usually located on the bottom of the transfer case. Place a pan under the drain plug and remove it.
- Allow the oil to drain completely. Clean off the plug and install it, tightening it until it is just snug.
- Remove the filler plug from the side of the case.
- Fill the transfer case with the correct oil through the filler plug hole as detailed previously. Refer to the Capacities chart for the amount of oil needed to refill your transfer case.
- The oil level should come right up to the edge of the hole.
- Install the filler plug with a new gasket, lower the truck, and check for leaks. Dispose of the old oil in the proper manner.