A shock absorber leaking oil or gas has reached the end of its life. If two leak at once, the car sways badly and replacement is needed.
Shock absorbers damp the oscillations of suspension springs; when they fail, the body keeps bouncing after bumps and the underbody and suspension can be damaged. There are three types: oil, gas-oil and gas.
Seals and gaskets keep oil or gas inside the cylinder. When the rod and seals wear, leaks begin: a gas unit stays dry while an oil unit gets wet. A leak shows the absorber is worn out or damaged by rough roads and needs replacing.
A single leaking strut may go unnoticed, but if two leak at once the car rocks noticeably even over small bumps and should be inspected.