Is your car making a loud noise instead of a low hum like it normally does? Have the differential fluids checked!
In a rear wheel drive vehicle, the rear differential has its own housing and lubrication. However, if you have a 4-wheel drive vehicle you have three differentials. The vehicle has one in the front, one in the back and one in the center of the car. The one located in the center of your vehicle is the transfer case. It helps adjust the speed differences between the front and rear wheels. This typically needs to be done every 30,000 to 50,000 miles. Refer to your owner’s manual for what is recommended for your car.