Your Chevrolet ball joints are the actual part that the wheels of your vehicle swivel on. This allows for the left and right turning of your car in a smooth and even motion. They are located at the end of the spindles in the lower and upper A-frames. As part of the routine maintenance conducted on your Chevrolet during an oil change, the zerk fittings on your car should have grease injected into them. Each ball joint has a zerk and must be greased to help keep it lubricated for long life of the part. For the grease to enter the ball joint effectively, the car should be on a lift with no pressure being applied to this steering part. With the new drive in oil change shops, this is not done and the amount of grease injected to your Chevrolet ball joints is very limited. Over time the lack of grease on the ball joints will cause them to wear or make the ball stud in the joint so loose that replacement of this part will become necessary. The dangers of this part wearing excessively on your Chevrolet can cause the bottom of the spindle to pop out of the jointly if a large obstruction is run over while your car is on the road. With most of the grease jobs are now performed with the car's wheel on the ground, it is the lower joint that is affected most by the lack of grease and will have the greatest amount of wear on them. Because the ball joints on your Chevrolet are set up in pairs, lower and upper, they should be changed as a pair even when one is not totally worn out. The replacement of these parts will help make your car safer plus an improved level of handling will be noticeable by the driver.