Centistokes (cSt) is the laboratory unit of kinematic viscosity used to rate silicone RC shock and gear-differential oils on a standardized scale.
Unlike Weight (WT) labels, which have no shared industry formula and shift by 25 to 50 cSt from one bottle brand to the next, centistokes measures how fast silicone fluid flows through a calibrated tube at a set temperature. Typical 1/10 RC shock oils fall between 250 cSt and 500 cSt (roughly 22.5 WT to 40 WT), while sealed gear differentials use 1,000 cSt to 500,000+ cSt fluid to control how aggressively power splits between inside and outside tires. Move shock oils in 50 cSt steps so the damping change is clear on the track, and avoid mixing two oil brands on opposite sides of the same car.
Logging silicone fluid in cSt alongside the bottle brand prevents surprise damping shifts when you copy a teammate's setup sheet across Associated, TLR, XRAY or Kyosho oils.