Differential housings contain gears that allow your wheels to turn at different rates while cornering to avoid locking and dragging one side or the other. These metal gears mesh together well, but do make contact and so are bathed in gear oil to lubricate their moving parts. Just like engine oil and transmission fluid, this oil degrades over time and with use.
Regular service is recommended to ensure proper and smooth differential operation. Worn differential gears and bearings will create rotational noise in your vehicle before failure. Phil’s is equipped to service your differential and rebuild the unit if need be. Instead of replacing your front differential or rear differential just service it with new fluid and keep it free of leaks for a long service life.