Shock oil is the silicone fluid inside your shock absorbers. Its weight controls how fast the shock compresses and rebounds, which changes how the car handles.

Follow your setup sheet as a starting point. Thicker oil slows the shocks for more grip on rough tracks, thinner oil frees them up on smooth surfaces.

Refresh it when handling drifts off or the oil looks dark or thin. Racers often change it every few race days for consistent damping.

Fill the body, move the shaft slowly to release air bubbles, let it settle, then bleed and cap. Doing both shocks on an axle the same way keeps them matched.