FLUID RECOMMENDATIONS AND LEVEL CHECK
See Figures 1, 2, 3 and 4
The oil in the differential should be checked at least every 6,000 miles on 1964-74 vehicles or every 7,500 miles for 1975 and later models.
- With the car parked on a level surface and with the parking brake set or with the vehicle raised and supported safely by 4 jackstands so the vehicle is level, remove the filler plug from the front side of the differential.
- If oil begins to trickle out of the hole, there is enough. Otherwise, carefully insert your finger into the hole (watch out for sharp threads) and check that the oil is up 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. Some gear oil manufacturers will provide a small hand-pump and length of tubing which can be used to pump gear oil into the housing. You can even use a common kitchen baster. Use only standard GL-5 hypoid-type gear oil - SAE 80W or SAE 80W/90.
On all models equipped with the positraction/limited slip rear axle, GM recommends that you use only the special lubricant which is available at your local Chevrolet parts department.
DRAIN AND REFILL
See Figures 5, 6, 7, 8 and 9
There is no recommended change interval for the rear axle but it is always a good idea to change the fluid if you have purchased the car used or if it has been driven in water high enough to reach the axle.
- Either park the car on a level surface and set the parking brake, or if additional room is necessary for access to the housing, raise and support the rear of the vehicle using jackstands.
- Remove the filler plug.
- Place a large container underneath the rear axle. Clean the area surrounding the rear cover to help prevent dirt from entering the rear axle housing.
- Unscrew the retaining bolts and remove the rear cover. When removing the cover, a small prytool may be used at the base of the cover to gently pry it back from the axle housing, breaking the gasket seal and allowing the lubricant to drain out into the container. Be careful not to use excessive force and damage the cover or housing.
- Carefully clean the gasket mating surfaces of the cover and axle housing of any remaining gasket or sealer.
- Install the rear cover using a new gasket and sealant. Tighten the retaining bolts using a crosswise pattern.
Make sure the vehicle is level before attempting to add fluid to the rear axle or an incorrect fluid level will result.
- Refill the rear axle housing using the proper grade and quantity of lubricant as detailed earlier in this section. Install the filler plug, operate the vehicle and check for any leaks.