Also called differential oil or gearbox oil, this heavy lubricating oil keeps the complex set of gears inside your car's differential (or gearbox) humming along. A differential is simply a set of gears that divides power from the engine and sends it to each of the drive wheels. While some front-wheel-drive vehicles have the differential integrated with the transmission, rear-wheel-drive vehicles like SUV's and pickups all have a rear differential.
Most automakers recommend replacing differential fluid at specified intervals, but if you use your vehicle to tow a trailer it is generally advised to have the differential fluid serviced at shorter-than-standard intervals (something noted in many owner's manuals). Plus, if the vehicle has been driven in water deep enough to submerge the differential, it is recommended that the differential fluid be changed as soon as possible to ensure that any water-contaminated fluid is removed and replaced with fresh fluid. (Note: Four-wheel-drive vehicles use a gearbox known as a transfer case to help split power between the front and rear wheels. Many transfer case fluids are similar or identical to differential fluids, and require similar service intervals).
If your differential (or transfer case) oil is due for replacement Einstein's can perform the service quickly and inexpensively. You never need an appointment and we're open seven days a week for your convenience. Every Einstein's service also meets your factory warranty requirements. Plus you can relax in your car with a FREE newspaper, beverage, and Wi-Fi while you watch your service performed live on TV! See a complete list of our services, packages, and prices at http://www.einsteinsoilery.com/services.
The above was written by Garrett McKinnon and was published in the Fall 2011 edition of Vehicle MD.