How often you should change front and rear differential fluid depends on your vehicle, driving conditions and differential fluid quality. That’s a vague answer, but it’s true. If you drive your truck primarily on the highway in temperate conditions and rarely tow or haul, you likely don’t need to change front or rear differential fluid
Changing gear oil in differentials and manual transmissions is critical for smooth operatation and reduced maintenance. But professional mechanics and DIY enthusiasts agree: changing gear oil is a hassle.