Most manufacturers recommend that the differential fluid be changed every 30,000 to 60,000 miles. It is a messy job, and should be done by a licensed mechanic.

What happens if you don't change your differential fluid?

Most differentials need a fluid change at about 50,000 miles. If left too long or if the fluid starts to run low, the differential will become noisy and can eventually fail. If that happens, the gears can seize, locking up the rear wheels and potentially causing a lot of damage or even an accident.

Is it necessary to change differential fluid?

Because the differential is at the rear and under the car, it gets none of the star treatment that the engine up front does. But if lubrication in the car differential fails, you won't be getting very far for very long. Fortunately, you only need to change this oil every 30,000 to 50,000 miles.