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Differential Service – Why Is It Important?

Of all the various things on a vehicle that need regular service and maintenance, the differential is too often neglected. But what exactly is it, and what does it do?

Visualize a rear-wheel-drive vehicle making a right-hand turn. As the car turns to the right, the left rear wheel will have to actually cover a longer distance and spin at a different speed than the right wheel. If the rear axle was delivering the same torque to both wheels, the left rear wheel would be binding and skittering as it made the turn. The differential is designed to allow the wheels to turn at different speeds around corners, eliminating that problem.

The differential uses an oil thicker than motor oil, somewhere between an oil and a grease in terms of its weight. Like any other assembly, though, the oil in the differential will become contaminated over time and will start to break down due to heat. 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.

Differentials have a fill hole, sometimes covered with a rubber plug that makes it easy to check the oil level. They don’t, however, have a drain plug, meaning that the only way to change the oil is to remove the differential’s rear cover. This is inevitably a messy job that’s best left to professionals. Remember also that on 4WD vehicles, there’s a second differential for the front wheels. For 4WD vehicles, it’s usually a good idea to perform service on both differentials and the transfer case at the same time.

If you’re in need of any kind of oil-change service, whether it’s motor oil, transmission fluid flush or differential service, you can count on us. Your car’s fluids are too important to neglect – make an appointment with us, and make differential fluid service part of your car’s regular preventive maintenance schedule.