Purpose of the Differentials / Gear box

The 4×4 system includes differentials and sometimes a transfer case, which all generate power to the wheels. The differential works with your transmission to deliver power from the engine to the axle that turns your wheels. Using a series of gears, the differential allows the wheels to turn at different speeds (the outside wheels need to turn faster than the inside wheels during a turn), enabling corner turning with improved traction.

Why change the Differential and Transfer Case fluid

High operating temperatures can cause the differential fluid to break down. When this happens, the gears won’t work together smoothly. If the differential gears start to grind together, continued driving can cause expensive damage. Replacing the old contaminated fluid with new fluid improves operation and extends the life of your differential.


  • Extends the life of the differential
  • Protects against rust and corrosion in the differential
  • Cleans, cools, and lubricates components
  • Helps avoid costly drive train repairs

How Often to change Differential and Transfer Case fluid

In accordance with your vehicles recommended service intervals which can be found in your owners manual, or by visiting any one of our oil change centers. NOTE: Services vary by location. Please call ahead to ensure the services you require are available at your local Pennzoil / Twins Oil Change Center.