Differential
How Differential Gear Works
Watch Video Source: ConceptVBS
How to Change Rear Differential Fluid (Detailed Version)
Watch Video Source: ChrisFix
How to Replace a Front Wheel Drive Axle
Watch Video Source: EricTheCarGuy
Symptoms of Bad or Failing Differential / Gear Oil
https://www.yourmechanic.com/article/symptoms-of-bad-or-failing-differential-gear-oil
If your car has exceeded its gear oil service interval, or if you hear the differential whining, you may need to replace the differential/gear oil.
Differential: Operation, Functions, Parts
http://www.learnengineering.org/2014/05/working-of-differential.html
Learn topics in mechanical, electrical and civil engineering through interactive video lessons!
How to Care For Your Car’s Differential
http://www.popularmechanics.com/cars/how-to/g1140/how-to-care-for-your-cars-differential/
You change your engine oil every few thousand miles, but have you ever looked at your differential?