Gas shocks are designed with nitrogen gas inside of them. These are more equipped to fit smaller cars and can take a beating from the road’s hardest and most severe bumps. Generally, you’ll find newer cars are fitted with gas shocks.
One of the telltale signs of a suspension system that requires service is unusual noise. As shocks and bushings wear, they lose their ability to properly support the strut. ... When the strut bottoms out, the metal-to-metal contact can cause a knocking sound that emanates from the front or rear wheels.
Since a car's shocks are responsible for controlling the impact and vibration of a vehicle's springs and suspension, worn ones won't be able to soften the blows of the road. A rattlin' ride is not only uncomfortable—it can put undue pressure on other parts of the car and could soon lead to more than shock troubles.