Last reviewed: November 13, 2026 · By the RaceYear team
Short answer: Centistokes (cSt) measures actual kinematic fluid viscosity in laboratory units, while Weight (WT) is a non-standardized bottle label that varies by brand. As a baseline rule in 1/10 RC shocks, 30 WT is roughly 350 cSt, 32.5 WT (Associated) is ~400 cSt, and 35 WT (TLR) is ~400 cSt. Always log both the brand and the cSt number on your RacerRX setup sheet so you can repeat damping feel accurately.
Key takeaways
Use this cross-reference table when copying a setup sheet across brands. Values reflect commonly published manufacturer bottle ratings and viscosity cross-references; always avoid mixing two different brands on opposite left/right corners of the same axle.
| Kinematic Viscosity (cSt) | Team Associated (WT) | Losi / TLR (WT) | XRAY / Kyosho / Metric | Typical 1/10 RC Use |
|---|---|---|---|---|
| 100 cSt | 10 WT | 15 WT (~104 cSt) | 100 cSt | Ultra-light pan car center dampener or frigid outdoor play |
| 150 cSt | 15 WT | 17.5 WT | 150 cSt | 1/12 pan car front/center micro shocks |
| 200 cSt | 20 WT | 20 WT | 200 cSt | Light oval / low-grip rough dirt |
| 250 cSt | 22.5 WT | 25 WT | 250 cSt | Slick dirt oval rear shocks, soft 2WD rear baseline |
| 300 cSt | 25 WT | 27.5 WT | 300 cSt | 1/10 2WD buggy rear on low-to-medium grip clay |
| 350 cSt | 30 WT | 30 WT | 350 cSt | Universal 1/10 buggy & Mudboss rear starting baseline |
| 400 cSt | 32.5 WT | 35 WT | 400 cSt | 1/10 2WD/4WD buggy front on clay; high-grip rear |
| 425 cSt | 35 WT | Between 35 & 37.5 WT | ~425 cSt | High-grip clay front or carpet buggy rear |
| 450 cSt | 37.5 WT | 37.5 WT | 450 cSt | High-grip carpet / astro 1/10 front shocks |
| 500 cSt | 40 WT | 40 WT | 500 cSt | High-bite carpet front or heavy 1/8 scale buggy |
| 550 cSt | 42.5 WT | 45 WT | 550 cSt | 1/8 buggy & truggy medium-temp outdoor |
| 600 cSt | 47.5 WT | Between 45 & 50 WT | 600 cSt | 1/8 off-road warm weather / big jumps |
| 650 cSt | 50 WT | 55 WT | 650 cSt | 1/8 truggy front or hot summer outdoor |
| 800 cSt | 60 WT | ~70 WT | 800 cSt | Heavy touring car / speed-run / drag damping |
| 1000 cSt | 80 WT | ~95 WT | 1000 cSt | Pan car side tubes or light gear-diff fluid |
Shock oil weight controls how fast weight transfers, not how much total weight transfers in steady-state cornering. Thicker oil (higher cSt) slows suspension movement down: the car feels flatter, jumps and lands without slapping the chassis, and responds faster to initial steering input on smooth high-grip carpet, at the cost of losing mechanical grip over sharp ruts.
Thinner oil (lower cSt) lets the tires follow bumps and generate faster mechanical traction on slick dirt or dusty clay, though going too thin lets the chassis roll too abruptly and bottom out on flat landings. For deeper spring and ride-height pairing, read our guide on RC shock oil, springs and ride height.
A 400 cSt oil behind a 2 x 1.6 mm piston feels totally different than 400 cSt behind a 3 x 1.4 mm piston. Smaller piston holes build more high-speed damping resistance (called pack) on jump faces and hard landings while staying supple in slow corner roll. Whenever you log a shock rebuild in RacerRX, save four details together: oil brand, WT/cSt rating, piston hole count and diameter, and ambient pit temperature.
They are slightly different physics units (centistokes vs centipoise, separated by silicone fluid density around 0.96 to 0.97), so a 400 cP oil is roughly 412 cSt. Never mix cP and cSt bottles blindly across left and right shocks, and stick to one brand across all four corners when possible.
Move in steps of 50 cSt (or 2.5 to 5 WT). Smaller changes than 25 cSt are almost impossible to feel on the driver’s stand once track grip shifts.
Pure silicone fluid resists breakdown well, yet aluminum shock bore wear and dirt pulled past O-ring seals contaminate the oil within a few race days. Fresh grey oil will feel noticeably more consistent after a rebuild.
Use RaceYear’s free RC gear ratio and rollout calculator and RC top speed calculator, or save every setup sheet offline in RacerRX (14-day free trial on iOS and Android).
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