RC shock oil weight to cSt chart: Associated, TLR, Kyosho & XRAY

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

• European and Japanese kits (XRAY, Kyosho, Mugen Seiki, Schumacher) specify silicone shock and differential oil in cSt (or nearly identical cP/cps).
• US brands (Team Associated Factory Team and Losi / Team Losi Racing) historically label shock oil in WT, though newer TLR bottles print both WT and cSt on the label.
• Because WT has no industry-wide formula, switching from 35 WT in one brand to 35 WT in another can change your damping by 25 to 50 cSt, roughly half a tuning step.
• Cold winter indoor pits thicken silicone oil; hot summer outdoor tracks thin it out by the equivalent of 2.5 to 5 WT.

RC silicone shock oil WT to cSt conversion chart

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

How shock oil viscosity changes RC handling

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.

Track piston holes alongside oil weight

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.

Frequently asked questions

Are cSt and cps the same for RC shock oil?

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.

How much should I change shock oil at a time?

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.

Does silicone shock oil wear out?

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.

Where can I run RC gearing and speed math?

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).

Sources

• PetitRC Silicone Oil Viscosity Comparison Chart, checked November 13, 2026: cross-brand WT and cSt silicone shock oil measurements across Associated, Losi and metric brands.
• RSRC Viscosity Converter from WT to CPS/cSt, checked November 13, 2026: kinematic viscosity definitions and brand consistency guidance.