Kyosho SIL0900 Silicone Shock Oil #900 40cc

Kyosho silicone shock oil in the #900 grade, supplied in a 40cc bottle.

Shock oil weight is the most direct way to change how quickly your suspension compresses and rebounds, and it works together with piston choice to set the overall damping character of the car. Heavier oil slows shaft movement, which controls big hits and stops the chassis bottoming out on hard landings. Taken too far, it makes the suspension pack down over successive bumps and lose grip. Lighter oil lets the suspension move freely and follow rough ground, at the cost of some control over jumps.

At #900 this is a heavy grade, generally used in larger-displacement shocks, in the front of a car needing more anti-dive, or on smooth high-speed tracks with big jump faces where landing control matters more than small-bump compliance.

Silicone is used because its viscosity changes very little as the shock warms through a run, so damping stays consistent from the first lap to the last. Note this is a shock oil grade; Kyosho's differential oils use a separate five- and six-digit numbering.