Use only standard GL-5 hypoid type gear oil: SAE 80W or SAE 80W/90.
The oil in the differential should be checked at least every 7,500 miles (15,000 miles, 1980 and later).
- With the car on a level surface, remove the filler plug from the back side of the differential.
- 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 that 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 is simple. You can also use a common kitchen baster. Use only the specified fluid.
- Replace the plug and check for leaks.
DRAIN & REFILL
The axle lubricant should be changed according to the schedule in the Maintenance Intervals chart. You may also want to change it if you have bought your car used, or if it has been driven in water deep enough to reach the axle.
- Park the car on a level surface. Place a pan of at least two quarts capacity underneath the drain plug. The drain plug is located on the center rear of the differential carrier, just below the filler plug on some models, on others it can be found at the bottom of the carrier. Remove the drain plug.
- Allow the lubricant to drain completely.
- Install the drain plug. Tighten it so that it will not leak, but do not overtighten. If you have a torque wrench, recommended torque is 29-43 ft. lbs.
- Refill the differential housing with API GL-5 gear oil of the proper viscosity. The correct level is to the edge of the filler hole.
- Install the filler plug. Tighten to 29-43 ft. lbs.