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How do I change the Differential Fluid?

Thanks to StealthV for this entire procedure

Click the images to make them larger

  • 1. Items Required:
  • -- Two quarts of GM PN-89021677- now grape scented- GM Synthetic Axle Lubricant SAE 75W-90 (~$27/quart) (old PN=#12378261 for reference)
  • -- One 4 oz. bottle of GM #1052358 Limited Slip Axle Lubricant Additive
  • -- One 10-mm hex allen wrench
  • -- Suction gun
  • -- Oil drain pan
  • -- Set of Rhino ramps or equivalent
  • -- Creeper to roll under car
  • -- Troublelight to see in the dark
  • -- One CTS-V (most important part!)

  • 2. Before the oil change, drive at least 10-15 miles at highway speeds to warm the differential.
    While working under the car, the engine, transmission, differential and exhaust will be extremely hot. Be careful, safety first!

  • 3. With the rear of the V safely supported, remove the fill plug first. The fill plug is located on the driver's side of the differential, half-way up the side of the differential housing and is a bit tricky to get at with the exhaust pipe in the way. Try using both ends of the 10-mm allen wrench to loosen the fill plug.

  • 4. Position the oil drain pan under the differential and remove the drain plug with the 10-mm allen wrench.
    Caution! Hot lubricant will come out quickly!

  • 5. While the differential housing is draining, clean up the drain plug. Here's the "before" shot of my plug. The dark glob on the end of the magnetic plug is the metallic paste that has formed from normal bevel pinion gear break-in.

  • 6. After the lube is done draining, install the clean magnetic drain plug and tighten snugly with the 10-mm allen wrench.

  • 7. Remove the top of the suction gun and fill it half full with the new GM diff lube. Pour in the bottle of limited slip additive and then continue to fill the suction gun body with diff lube until near the top of the gun. Place the top of the suction gun back on, go under the V, place the hose in the fill hole and press in the handle on the suction gun to push the fluid into the diff housing.
  • 8. Once the suction gun is empty, refill with diff lube and continue to fill the differential housing until lubricant begins to spill out of the hole.
  • 9. Reinstall the fill plug and tighten until snug.

  • 10. Clean up your mess, safely lower the V and take it for a spin and enjoy the knowledge that for not much money, you've done your differential a favor!

  • This site is not affiliated with General Motors or Cadillac. All trademarks are property of their respective owners.
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