How often do I need to change my vehicle's differential fluid?

Many people don't even know what a differential does. It's not one of those normal car parts like a transmission or a radiator. In fact, some people drive a car all their lives without knowing what a differential is...

Many people don't even know what a differential does. It's not one of those normal car parts like a transmission or a radiator. In fact, some people drive a car all their lives without knowing what a differential does.

What does a differential do?

Remember how people ran on the treadmill during the Olympics? In longer races, after everyone has started in their respective lanes, everyone is grouped into the inside lane of the track. This is because at the corners, only the inner lane is 400 meters long. If runners were to run in their lane for a 400m race, the runner in the outer lane would actually have to run 408m.

When a car is cornering, the same scientific principle applies. As the car goes through a turn, the wheel on the outside of the turn covers more ground than the wheel on the inside of the turn. Although the difference is negligible, a car is an accurate vehicle and small deviations can cause a lot of damage in the long run. The differential compensates for this difference. Differential fluid is a thick, dense fluid designed to lubricate the differential as it compensates for all the turns the car makes.

How often do I need to change the differential fluid?

Most manufacturers recommend changing the differential fluid every 30,000-60,000 miles. This is a dirty job and should be done by a licensed mechanic. The fluid will have to be disposed of properly, you may need a new gasket, and the parts inside the differential housing will need to be wiped down to prevent any contamination from the old fluid from getting into the new one. Also, since the differential is under the car, it will need to be raised, so this is definitely not a DIY project.