Differential Service

Drain and replace the rear differential fluid on a 2007-2013 Mercedes-Benz S65 AMG to maintain proper lubrication and extend differential life.

Warnings

Tools required

Parts

• Drain plug washer × 1 — A0009831325 or equivalent
• Fill plug washer × 1 — A0009831325 or equivalent

Fluids

• Mercedes-Benz Diff Fluid 75W-85 — 2 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Place wheel chocks in front of front wheels
3. Allow differential to cool to warm (not hot) temperature for easier draining
4. Raise rear of vehicle with floor jack and secure on jack stands at manufacturer lift points
5. Ensure vehicle is level front-to-back for accurate fill level

Procedure

1. 1

   Locate drain and fill plugs
   Position yourself under the rear differential housing. Locate the drain plug on the bottom of the differential housing and the fill plug on the driver's side of the housing. Clean the area around both plugs with a wire brush and brake cleaner to prevent contamination.
2. 2

   Loosen fill plug first
   Using a 13mm hex bit, loosen the fill plug 1-2 turns but do not remove. This ensures you can refill the differential after draining. If the fill plug is seized and cannot be loosened, do not proceed with draining.
   ⚠Always loosen the fill plug before draining. If the fill plug is seized, you will not be able to refill the differential.
3. 3

   Drain differential fluid
   Position drain pan under the drain plug. Using a 13mm hex bit, remove the drain plug completely along with its washer. Allow fluid to drain completely for at least 10 minutes. Inspect the drained fluid for metal particles or contamination which may indicate internal wear.
   Torque spec

   Drain Plug55 Nm (41 lb-ft)
4. 4

   Clean and reinstall drain plug
   Clean the drain plug threads and magnetic tip with brake cleaner and a shop rag. Inspect the drain hole threads for damage. Install a new washer on the drain plug and thread it in by hand to ensure proper thread engagement. Torque to specification.
   ⚠Always use a new washer on the drain plug. Reusing old washers can result in leaks.
   Torque spec

   Drain Plug55 Nm (41 lb-ft)
5. 5

   Remove fill plug
   Fully remove the fill plug and washer from the side of the differential housing. Verify the vehicle is level to ensure proper fill level accuracy.
6. 6

   Fill differential with new fluid
   Using a fluid transfer pump or squeeze bottle, inject Mercedes-Benz 75W-85 differential fluid into the fill hole until fluid begins to drip out of the fill hole. This indicates the differential is full to the proper level. Allow fluid to stabilize for 30 seconds.
   ℹ️Only use Mercedes-Benz approved 75W-85 differential fluid. Other fluids may damage the limited-slip differential clutches.
7. 7

   Reinstall fill plug
   Clean the fill plug threads with a shop rag. Install a new washer on the fill plug and thread it in by hand. Torque to specification. Wipe any spilled fluid from the differential housing.
   Torque spec

   Fill Plug55 Nm (41 lb-ft)
8. 8

   Lower vehicle and clean up
   Remove jack stands and carefully lower the vehicle to the ground. Dispose of used differential fluid properly at a recycling center or auto parts store. Clean all tools and work area.

Reassembly

1. Ensure both drain and fill plugs are torqued to specification with new washers installed
2. Verify no fluid leaks are present around either plug
3. Dispose of old differential fluid according to local environmental regulations

Verification

• Start the vehicle and allow it to idle for 1 minute, then shift through all gear positions
• Drive the vehicle for 5-10 miles and recheck both plugs for any signs of leakage
• Listen for any unusual noises from the differential during operation, particularly during turns
• After initial test drive, verify no fluid drips are present on the garage floor under the differential

Related trouble codes on this vehicle

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