The differential controls the speed of the left and right wheels on your vehicle.
It allows them to rotate at different speeds while making turns, as the outer wheel path is longer in distance than the inner wheel.
As a result the differential is subject to friction and heat, which over time will break down the additives in the differential fluid.
Wear particles from the clutch as well as condensation also mix with the fluid, causing the fluid to further break down.
Differential Service removes old contaminated fluid and replaces it with manufacturer approved fluid, , cleans the gear box and service areas.