This procedure drains and refills the rear differential with fresh synthetic gear oil to maintain proper lubrication and extend component life.

Warnings

Tools required

Parts

• Drain plug washer × 1 — Copper or aluminum crush washer - Use OEM specification

Fluids

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

Preparation

1. Park vehicle on level ground and engage parking brake
2. Allow differential to cool if vehicle was recently driven (minimum 30 minutes)
3. Raise rear of vehicle and support securely with jack stands on frame rails
4. Ensure adequate working clearance beneath vehicle
5. Locate the rear differential housing at center of rear axle - identify fill plug (upper) and drain plug (lower)

Procedure

1. 1

   Break fill plug loose
   Before draining, first loosen the fill plug on the front or side of the differential housing using a 10mm socket. This ensures you can refill the differential after draining. Do not fully remove yet, just break it loose to verify it will come out.
2. 2

   Position drain pan
   Place oil drain pan directly beneath the differential drain plug. Position pan to catch approximately 2 quarts of gear oil. The drain plug is located at the lowest point of the differential housing.
3. 3

   Remove drain plug
   Using a 10mm socket, slowly remove the drain plug from the bottom of the differential housing. Allow fluid to drain completely. Gear oil will be thick and may drain slowly, especially if cool. Inspect the drain plug and washer for damage or excessive metallic debris.
   ⚠Fluid may still be warm. Allow it to drain away from hands and arms.
4. 4

   Inspect drained fluid
   Examine the drained fluid for metal particles, unusual color, or water contamination. Small metallic particles are normal, but large chunks or excessive debris may indicate internal wear. Water contamination appears as milky fluid.
5. 5

   Clean and prepare drain plug
   Clean the drain plug threads with a shop rag. Discard the old crush washer and install the new copper or aluminum drain plug washer onto the drain plug. Ensure mating surface on differential housing is clean and free of debris.
6. 6

   Install drain plug
   Thread the drain plug with new washer into the differential housing by hand to avoid cross-threading. Tighten to specification using a torque wrench.
   Torque spec

   Drain Plug47 Nm (35 lb-ft)
7. 7

   Remove fill plug
   Completely remove the fill plug from the differential housing. The fill plug is typically located on the front face of the differential or on the side, approximately halfway up the housing.
8. 8

   Fill differential with gear oil
   Using a fluid transfer pump or squeeze bottle with extended hose, add Motorcraft 75W-140 Synthetic Gear Oil through the fill hole. Fill until gear oil begins to seep out of the fill hole opening. The differential is properly filled when fluid reaches the bottom of the fill plug threads. Total capacity is approximately 2.0 quarts.
9. 9

   Install fill plug
   Clean the fill plug threads and install it by hand. Tighten the fill plug to specification using a torque wrench. Wipe away any excess gear oil from the differential housing.
   Torque spec

   Fill Plug47 Nm (35 lb-ft)
10. 10

    Check for leaks
    Inspect both the drain plug and fill plug for any signs of leakage. Wipe the area clean with a shop rag and observe for several minutes to confirm no seepage.

Reassembly

1. Lower vehicle from jack stands to the ground
2. Remove jack stands and lower jack completely
3. Dispose of used gear oil properly at a recycling center or automotive parts store

Verification

• Start engine and allow to idle briefly, then shift through all gear positions
• Drive vehicle forward and reverse a short distance to circulate new fluid
• Re-check differential housing for any leaks around drain and fill plugs after short test drive
• Verify no unusual noises from rear differential during operation

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