This procedure drains and refills the rear differential fluid on 2016-2024 Hyundai Tucson AWD models with the 2.5L I4 engine to maintain proper lubrication and prevent component wear.

Warnings

Tools required

Parts

• Rear differential drain plug washer × 1 — Use OEM specification
• Rear differential 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 tires
3. Allow differential to cool if recently driven (at least 30 minutes)
4. Raise rear of vehicle and support securely on jack stands at manufacturer-specified lift points
5. Verify vehicle is stable before working underneath
6. Locate rear differential - positioned centrally between rear wheels with drain plug at bottom and fill plug on side

Procedure

1. 1

   Locate and clean drain and fill plugs
   Identify the drain plug on the bottom of the differential housing and the fill plug on the passenger side of the housing (typically 17mm hex head). Clean around both plugs with a wire brush to prevent contamination when opened.
2. 2

   Break loose fill plug first
   Using a 17mm wrench, carefully break loose the fill plug (upper plug) BEFORE removing the drain plug. This ensures you can refill the differential after draining. Do not fully remove yet, just verify it will turn. If fill plug is seized, do not proceed with draining until it can be opened.
   ⚠Always verify fill plug can be removed before draining to avoid being unable to refill the differential
3. 3

   Position drain pan and remove drain plug
   Position drain pan directly under the drain plug with at least 3 quart capacity. Using a 17mm wrench, fully remove the drain plug and allow all gear oil to drain completely. This may take 5-10 minutes. Inspect drained fluid for metal particles or unusual debris which may indicate differential wear.
4. 4

   Inspect and clean drain plug
   Inspect the drain plug for damage to threads or sealing surface. The drain plug is magnetic - clean all metal particles from the magnet using a clean rag. Remove and discard the old crush washer from the drain plug. Wipe the drain plug threads clean.
5. 5

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

   Mounting Bolts27 Nm (20 lb-ft)
6. 6

   Remove fill plug and prepare to fill
   Fully remove the fill plug from the side of the differential housing. Remove and discard the old crush washer. Wipe the fill plug threads clean and prepare fluid transfer pump or funnel with hose.
7. 7

   Refill differential with gear oil
   Using a fluid transfer pump or funnel with flexible hose, add 75W-90 GL-5 gear oil through the fill hole. Fill until oil begins to drip from the fill hole opening - this indicates the proper level. The differential should hold approximately 2.0 quarts. Allow excess to drain back out until dripping stops.
   ℹ️Proper fill level is reached when oil is at the bottom of the fill plug hole and begins to overflow
8. 8

   Reinstall fill plug
   Install a new crush washer onto the fill plug. Thread the fill plug by hand into the differential housing. Torque the fill plug to specification using a torque wrench. Wipe away any spilled gear oil from the differential housing.
   Torque spec

   Mounting Bolts27 Nm (20 lb-ft)
9. 9

   Lower vehicle and verify
   Lower the vehicle from jack stands to the ground. Start the engine and shift through all gear positions (P-R-N-D) while stationary. Drive the vehicle forward and reverse a few feet to circulate the new gear oil. Re-check the fill level if desired by raising vehicle and briefly removing fill plug to verify oil is at proper level.

Reassembly

1. Ensure both drain and fill plugs are torqued to specification with new crush washers installed
2. Verify no leaks around plugs after initial test drive
3. Dispose of used gear oil at an appropriate recycling facility - do not pour down drains

Verification

• Check for leaks around drain and fill plugs after first drive
• Verify smooth operation with no new whining or grinding noises from rear differential during turns
• After 50-100 miles of driving, recheck differential for any seepage around plugs
• Confirm proper fluid level by removing fill plug - oil should be at bottom edge of fill hole

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