This procedure drains and refills the rear differential with fresh synthetic gear oil, ensuring proper lubrication and longevity of the rear axle components.

Warnings

Tools required

Parts

• Drain plug washer × 1 — Use OEM specification

Fluids

• Motorcraft 75W-140 Synthetic Gear Oil — 2 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Allow differential to cool to warm (not hot) temperature for easier draining
3. Verify you have the correct Motorcraft 75W-140 synthetic gear oil (2 quarts required)
4. If additional clearance is needed, safely raise and support the rear of the vehicle on jack stands

Procedure

1. 1

   Locate differential drain and fill plugs
   Position yourself under the rear of the vehicle. The rear differential is located at the center of the rear axle. Identify the drain plug on the bottom of the differential housing and the fill plug on the upper side or rear face of the housing. Clean the area around both plugs with a wire brush to remove dirt and debris.
2. 2

   Remove fill plug first
   Using the appropriate socket, loosen and remove the fill plug BEFORE draining. This ensures you can refill the differential after draining. If the fill plug is seized and cannot be removed, do not proceed with draining. Set the fill plug aside in a clean area.
   ⚠Always remove the fill plug before the drain plug to avoid being unable to refill the differential.
3. 3

   Drain differential fluid
   Position the drain pan directly under the drain plug. Using the appropriate socket, slowly loosen the drain plug. Once loose, quickly remove it by hand, allowing the old gear oil to drain into the pan. The drain plug has a washer that must be replaced. Allow fluid to drain completely for at least 5-10 minutes.
   ⚠Fluid may be hot and will flow quickly once plug is removed. Keep hands clear of the stream.
4. 4

   Inspect and clean drain plug
   Inspect the drain plug threads and magnetic tip (if equipped) for metal debris. Excessive metal shavings may indicate internal wear. Remove the old washer from the drain plug and discard it. Clean the drain plug threads with a shop rag. Clean the drain plug hole area on the differential housing.
5. 5

   Install drain plug with new washer
   Install the new washer onto the drain plug. Thread the drain plug into the differential housing by hand to avoid cross-threading. Once hand-tight, use a torque wrench to tighten the drain plug to specification.
   Torque spec

   Drain Plug47 Nm (35 lb-ft)
6. 6

   Refill differential with fresh gear oil
   Using a fluid transfer pump or squeeze bottle, insert the nozzle into the fill plug hole. Slowly add Motorcraft 75W-140 synthetic gear oil until it begins to drip out of the fill hole. The differential is full when fluid reaches the bottom of the fill plug threads. Add approximately 2 quarts total.
   ℹ️Fill slowly to allow air to escape and prevent overfilling. Stop when fluid reaches the fill hole opening.
7. 7

   Install fill plug
   Wipe any excess gear oil from around the fill plug opening. Thread the fill plug into the housing by hand until snug. Use a torque wrench to tighten the fill plug to specification.
   Torque spec

   Fill Plug47 Nm (35 lb-ft)
8. 8

   Clean up and inspect for leaks
   Wipe down the differential housing with shop rags to remove any spilled gear oil. Properly dispose of the old gear oil at a recycling center or auto parts store. If vehicle was raised, carefully lower it to the ground.

Reassembly

1. No disassembly was required for this procedure beyond plug removal

Verification

• Start the engine and allow it to idle for 1-2 minutes
• Drive the vehicle forward and backward several feet to circulate the new gear oil
• Re-inspect the drain and fill plugs for any signs of leakage after the test drive
• Check underneath the vehicle after 50-100 miles of driving to confirm no leaks have developed

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