Cleaning your 1979 Chevy Custom Deluxe's rear differential properly requires a different approach:
1. Safety First: Never work under a vehicle supported only by a jack. Use jack stands rated for the weight of your vehicle to securely support it. This is crucial for your safety.
2. Locate the Differential Fill and Drain Plugs: These are usually on the bottom of the differential housing. The fill plug is usually higher than the drain plug.
3. Drain the Old Fluid: Place a drain pan under the drain plug and carefully remove the plug. Let the old fluid drain completely. This is the most effective way to remove dirt and debris from the differential.
4. Refill with Fresh Gear Oil: Once the old fluid has drained, replace the drain plug. Then, using a funnel, carefully add the correct type and amount of gear oil specified in your owner's manual. This is crucial for the proper operation and longevity of your differential. Using the wrong type of oil can cause serious damage.
5. Check the Fluid Level: Once refilled, check the level using the fill plug. It should be filled to the bottom of the fill hole. Do not overfill.
Important Considerations:
* Gear Oil Type: Your owner's manual will specify the correct type and weight of gear oil for your differential. Using the wrong type can cause damage. A common type for older vehicles is 80W-90.
* Differential Cover Gasket: When you drain the fluid, you may need to replace the differential cover gasket. Inspect it for damage; if it looks cracked or deformed, replace it.
The lube shop's suggestion was dangerous and ineffective. Avoid their advice. Following the steps above will properly clean and maintain your rear differential. If you are uncomfortable performing this task yourself, take your vehicle to a reputable mechanic or transmission shop.
