What's the dif? To an automotive technician, it's the differential, a part of your vehicle that helps direct power from the engine to the wheels.  The differential is a gearbox that enables the drive wheels to turn at different speeds (they do that when you turn).  

Inside the differential is a fluid that makes sure those gears and other parts are lubricated since there are a lot of metal moving parts in there.  (Your vehicle may have more than one differential in it depending on the drivetrain.) 

As you can imagine, it's important that the lubricant in those differentials do its job.  Otherwise, the gears may be damaged by heat and friction. The more you drive your vehicle, the more likely it is for that lubricating fluid to break down.

So, it's important to have the differential fluid exchanged every so often.  Your vehicle's manufacturer recommends how often your model should have that done, but a common interval is every 30,000-60,000 miles/50,000 km-100,000km.  Regular exchange of differential fluid can reduce premature wear of the gears inside.

Scheduled maintenance goes a long way to preventing differential problems, but sometimes when they begin to fail, you may hear the vehicle sounding a little louder than usual where the differentials are located.  

When it comes to changing the differential fluid, some have a drain plug in them. Others require the entire cover to be removed to drain the fluid.  There are often gaskets that must be changed at the same time to make sure there are no leaks.
Now when someone asks you, "What's the dif?" You’ll know how essential the differential is and how to keep it running in top shape.

Auto Lab Troy
2790 West Maple Rd.
Troy, Michigan 48084
(248) 643-7690