This procedure drains and refills the rear differential fluid on an AWD 2016-2024 Hyundai Tucson with the 2.5L I4 engine to maintain proper lubrication and extend differential lifespan.

Warnings

Tools required

Parts

• Drain plug washer × 1 — Use OEM specification
• Fill plug washer × 1 — Use OEM specification

Fluids

• 75W-90 GL-5 Gear Oil — 2 qt

Preparation

1. Park vehicle on level ground and engage parking brake
2. Place wheel chocks in front of front wheels
3. Allow differential to cool to warm (not hot) if recently driven
4. Raise rear of vehicle using jack and support securely on jack stands at manufacturer-recommended lift points
5. Ensure vehicle is level front-to-back for accurate fill procedure
6. Locate rear differential under center of vehicle between rear wheels

Procedure

1. 1

   Access drain and fill plugs
   Identify the drain plug on the bottom of the rear differential housing and the fill plug on the side or back of the housing. Clean the area around both plugs with a wire brush and shop rag to prevent contamination when removed.
2. 2

   Loosen fill plug first
   Using a 17mm socket or wrench, loosen the fill plug BEFORE draining to ensure you can refill the differential. If the fill plug is seized and cannot be removed, do not proceed with draining. Break the fill plug loose but leave it in place.
   ⚠Always verify the fill plug can be removed before draining. A seized fill plug will leave you unable to refill the differential.
3. 3

   Drain differential fluid
   Position drain pan under the drain plug. Remove the drain plug completely using the 17mm socket. Allow all fluid to drain completely, which may take 5-10 minutes. Inspect the drained fluid for metal particles or debris that could indicate wear.
4. 4

   Install drain plug with new washer
   Remove the old washer from the drain plug and discard. Install the new drain plug washer onto the drain plug. Clean the drain plug threads and sealing surface on the differential housing with a shop rag. Thread the drain plug in by hand to prevent cross-threading, then torque to specification.
   Torque spec

   Drain Plug41 Nm (30 lb-ft)
5. 5

   Remove fill plug
   Completely remove the fill plug from the differential housing. Inspect and replace the fill plug washer if damaged or if a new washer is included with your fluid purchase.
6. 6

   Fill differential with gear oil
   Using a fluid transfer pump or squeeze bottle, add 75W-90 GL-5 gear oil through the fill hole. Fill until oil begins to flow out of the fill hole. The differential is properly filled when oil reaches the bottom of the fill plug opening. Total capacity is approximately 2.0 quarts.
   ℹ️Vehicle must be level for accurate fill. Oil should just begin to drip from fill hole when at proper level.
7. 7

   Install fill plug
   Install the new fill plug washer if not already done. Wipe any excess oil from the fill plug area. Thread the fill plug in by hand, then torque to specification.
   Torque spec

   Fill Plug41 Nm (30 lb-ft)
8. 8

   Clean and lower vehicle
   Wipe down the differential housing to remove any spilled gear oil. Check both drain and fill plugs for leaks. Carefully lower the vehicle from jack stands and remove jack stands. Lower vehicle completely to the ground.

Reassembly

1. Ensure both drain and fill plugs are torqued to specification with new washers installed
2. Dispose of used gear oil properly at a recycling center or auto parts store
3. Record the service in your maintenance log with date and mileage

Verification

• Start the engine and let it idle for 30 seconds, then turn off
• Check underneath the differential for any signs of leaking from drain or fill plugs
• Test drive the vehicle for 5-10 minutes, listening for any unusual noises from the rear differential
• Re-check for leaks after test drive with vehicle on level ground
• Verify smooth operation during turns and acceleration with no binding or unusual noises

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