Normal vehicle wear causes differential fluid to increase in temperature, which causes fluid breakdown and loss of lubricating ability. Maintaining your differential / gearbox protects against abnormal wear caused by fluid breakdown and sludge build-up that can cause major failures and costly repairs.

Rear differential service involves draining and refilling the gear oil housed in the differential. The rear differential is responsible for transferring power to the ground on rear- and four-wheel-drive vehicles. The gear oil in the rear differential lubricates and prevents wear in the rear end gears. In addition to transferring the engine's power to the ground, the rear differential allows the rear wheels to spin at different speeds, as is necessary when cornering.