Tools and Materials You'll Need:
* Jack and jack stands: Safety first! Never work under a car supported only by a jack.
* Wheel chocks: Essential for added safety.
* Drain pan: To catch the old oil.
* Wrench for the drain plug: Likely a 10mm or 11mm, but check your owner's manual.
* Wrench for the fill plug: Usually the same size as the drain plug, but sometimes different.
* Torque wrench: To tighten the drain and fill plugs to the correct specification (found in your owner's manual). Improper tightening can lead to leaks or stripped threads.
* New differential oil: The correct type and quantity for your differential (check your owner's manual – it's usually 75W-140 gear oil).
* Funnel: To make filling easier.
* Gloves: To keep your hands clean.
* Rags or shop towels: To clean up spills.
* Impact Wrench (Optional but highly recommended): The drain and fill plugs can be very tight. An impact wrench makes this significantly easier.
Procedure:
1. Safety First: Park your Mustang on a level surface, engage the parking brake, and chock the rear wheels. Wear safety glasses.
2. Locate the Differential: The differential is located at the rear of the vehicle, in the rear axle housing.
3. Jack Up the Car: Safely jack up the rear of the car and secure it on jack stands.
4. Locate the Drain Plug: It's usually on the bottom of the differential housing. Clean the area around the plug with a rag to prevent debris from falling into the differential.
5. Drain the Old Oil: Carefully loosen the drain plug with the appropriate wrench. Once it's loose, carefully unscrew it by hand to avoid dropping it. Let the oil drain completely into your drain pan. This can take 15-30 minutes.
6. Locate the Fill Plug: The fill plug is usually located on the top or side of the differential housing. It might be easier to locate after you remove the drain plug. Try to loosen it *before* draining the old oil, in case it's seized.
7. Clean the Drain Plug and Replace: Clean the drain plug and reinstall it, tightening it to the manufacturer's specified torque (found in your owner's manual). Do not overtighten!
8. Fill with New Oil: Using a funnel, carefully pour the correct amount of new differential oil into the fill hole. Refer to your owner's manual for the exact capacity. You may need to use a pump to get the oil into the fill hole.
9. Check the Oil Level: Once you've added the oil, check the level. The fill plug should be near the bottom of the fill hole, and the oil level should be at or just below the fill hole's opening. You'll likely need to add oil until it starts seeping out of the fill hole.
10. Install the Fill Plug: Tighten the fill plug to the manufacturer's specified torque.
11. Lower the Car: Carefully lower the car from the jack stands.
12. Check for Leaks: After lowering the car, inspect the area around both plugs for any leaks.
13. Dispose of Old Oil Properly: Take the used differential oil to a recycling center or auto parts store that accepts used oil.
Important Considerations:
* Torque Specifications: Following the correct torque specifications is crucial to prevent leaks and damage.
* Type of Oil: Use the correct type and weight of gear oil specified in your owner's manual.
* Safety: Always prioritize safety. Use jack stands, chock the wheels, and wear appropriate safety gear.
If you're uncomfortable performing this task yourself, it's always best to take your Mustang to a qualified mechanic. They have the experience and tools to do the job safely and correctly.
