Fork oil weights

The real story...

This table is sorted by real viscosity (centiStokes), not by nominal weight. Note that the nominal weight is ... um... not really in the same order as the real weight.

The other interesting number is the Viscosity Index (VI), which is how stable the viscosity is over a wide temperature range. Bigger numbers are better. It doesn't just mean hot-day vs. cold day, it means begining of race vs. end.
Brand / weight / modelnominal weight Reported cSt @40C (centiStokes) Reported cSt @100C (centiStokes)Reported Viscosity Index (VI)Recaclulated Viscosity Index (VI)Viscosity/ Temperature Coefficient (VTC)VT (cSt@40/cSt@100)sourcenotes
Red Line (like water, Clear)1 5.50 2.33443430.582.39PVD
Red Line (extra light, Blue)2.5 9.80 44024030.592.45PVD
Spectro, Golden (ultra light)- 10.40 4.43854400.582.36PVD
RockShox (2.5w Light cartridge (Torco 5)2.5 10.75 43253400.632.69PVD
Torco RFF 55 10.75 43253400.632.69PVD
Bel-Ray HVI (3 wt)3 11.00 3.852962970.652.86PVD
Kayaba (K2-S shock)- 11.30 43103100.652.83PVD
Showa Suspension Fluid SS-25 (2.5wt. Stock Shock, OEM)2.5 12.50 3.92392390.693.21PVD
Silkolene Pro RSF (2.5wt)2.5 13.60 5.834644650.572.33PVD
…hlins Shock Absorber Fluid No. 309 (#01306-01)- 13.70 -----PVD
Maxmia Racing Shock fluid (light, red)3 13.90 5.2359--2.67Maxima
Maxima Racing Shock Fluid (light, 3wt)3 14.00 5.23783700.632.69PVD
Torco RSF Light (purple)- 14.50 4.72882860.683.09PVD
PJ1 Cartridge Pro For Fluid (3.5 wt)3.5 14.60 3.6-1340.754.06PVD
Castrol Fork Oil (10wt)10 15.00 41501790.733.75PVD
Motorex Racing Fork Oil (2.5w)2.5 15.10 4.2200---PVD
RaceTech (Motorex) (Light US1)4.25 15.20 4.42222260.713.45PVD
Kawasaki (KHL-15-10)- 15.30 -----PVD
Penske (lightweight shock fluid)- 15.50 6.34344340.592.46PVD
Suzuki (Fork L01)- 15.50 -----PVD
Kayaba 01 (zero-One Fork)- 15.60 3.45150960.784.52PVD
Yamaha 01 Fork oil (Kayaba)- 15.60 3.45150960.784.52PVD
Showa Suspension Fluid SS-05 (Stock fork, OEM)- 15.65 3.61161130.774.36PVD
Maxima Bicycle Fork fluid (5wt)5 15.90 3.51150980.785.53PVD
Maxima Fork oil (5 wt)5 15.90 3.51150980.784.53PVD
Maxima Racing Fork fluid (85/150, 5 wt)5 15.90 3.51150980.784.53PVD
Motul Fork Oil (Very Light ) ??- 16.00 3.5100950.784.57PVD
Rockshox (5w Medium, Hydracoil) (Torco 7)7 16.10 5.052852800.693.19PVD
Torco RFF 77 16.10 5.052852800.693.19PVD
Motul Shock Oil (2.5-20)- 16.10 6.24004030.612.6PVD
Maxima Racing Fork Fluid 85/150 (green)5 16.20 4.41202--3.67Maxima
Maxima Fork Oil5 16.20 4.41202--3.67Maxima
showa Suspension Fluid SS-07 (5wt) (Apolo)5 16.44 3.761351190.774.37PVD
…hlins Front Fork Fluid (No. 5 #1305-01)- 16.50 ---0.28-PVD
Suzuki (Fork W-15)- 16.80 -----PVD
Spectro, Golden Spectro cartridge Fork Fluid (85/150 Very light)- 16.90 3.821501190.774.42PVD
Honda Pro HP Fork Oil (5wt)5 17.00 3.81401150.784.47PVD
Pro-Circuit PC-01- 17.00 4.1-1490.764.15PVD
Bel-Ray Fork Oil (5 wt)5 17.10 4.11461470.764.17PVD
Kayaba G55 17.70 3.572720.85.06PVD
Yamaha (Suspension G5)5 17.70 -----PVD
Kawasaki (Fork G5)5 17.90 -----PVD
ELF Moto Fork oil SYN (2.5)2.5 18.00 41211220.784.5PVD
Motul Fork Oil, Comfort (Light, 5)5 18.20 41241190.784.55PVD
Motul Fork Oil, Factory Line (Light, 5)5 18.30 4.21381380.774.36PVD
Red Line (Light, Yellow)5 18.40 7.14074090.612.59PVD
Agip Fork (2.5 wt)2.5 18.50 4.371521530.764.23PVD
…hlins Front Fork Flulid (R&T 43, #1309-01)- 19.00 ---0.32-PVD
Bardahl (5w Fork Oil)- 19.30 5.12122120.743.78PVD
Bel-Ray HVI (5wt)5 19.50 6.663453450.662.93PVD
Torco RFF 1010 19.90 5.72602560.713.49PVD
Motul Fork Oil (Light)??- 20.00 62602800.73.33PVD
Showa Suspension Fluid SS-15- 20.07 ---0.33-PVD
Maxima Racing Shock Fluid Medium (purple)7 20.76 7.28338--2.85Maxima
Spectro, SX "400"- 20.90 8.94004600.572.35PVD
Maxima Racing Shock Fluid (Medium, 7wt)7 21.00 7.33493580.652.88PVD
Spectro Fork Oil (5wt)5 21.60 4.41191140.84.91PVD
Agip Fork (5wt)5 22.00 5.21751780.764.23PVD
…hlins Front Fork Fluid (No. 10, #1310-01)10 22.00 ---0.37-PVD
Silkolene Fork Oil (5wt)5 22.30 4.41061070.85.07PVD
Motul Fork Oil, Factory Line (Medium, 5-10)7.5 22.30 6.22542530.723.6PVD
Motorex Racing Fork Oil (5w)5 22.60 5.6200---PVD
Elf Moto Fork OIL SYN (5)5 23.30 4.81301290.794.85PVD
PJ1 Fork Tuner (2.5wt)2.5 26.10 4.9-1110.815.33PVD
(Marzzochi)- 26.10 5.251501350.84.97PVD
Spectro, Golden Spectro Cartridge Fork Fluid (125/150, Very Light) (Marzzochi)- 26.10 5.251501350.84.97PVDwhat is this?
Spectro, Golden (Very Light)- 26.40 9.94003970.632.67PVD
Maxima Racing Fork Fluid (125/150), 7wt)7 26.70 5.361511380.84.98PVD
Silkolene Pro RSF (5wt)5 26.70 9.463723720.652.82PVD
Maxima Racing Fork Fluid 125/150 (blue)7 26.70 5.36151--4.98Maxima
PJ1 Fork Tuner (7.5wt)7.5 27.50 5.1-1130.815.39PVD
Castrol Synthetic Fork Oil (5wt)5 28.00 5.71511490.84.91PVD
…hlins Shock Absorber Fluid No. 131 (#00105-01)- 28.70 9.43403400.673.05PVD
Maxima Racing Shock Fluid Heavy (clear)10 28.94 9.36300--3.09Maxima
Bel-Ray Fork Oil (7wt)7 29.00 5.21101080.825.58PVD
Maxima Racing Shock Fluid (Heavy, 10wt)10 29.00 9.43343360.683.09PVD
…hlins (High Performance)- 30.25 10.183523520.662.97PVDwhat is this?
Red Line (Medium, Red)10 30.40 10.83693740.642.81PVD
…hlins Front Fork Fluid (No. 15, #1315-01)- 30.70 ---0.51-PVD
Agip Fork (7.5wt)7.5 31.00 6.41631650.794.84PVD
PJ1 Fork Tuner (5wt)5 31.20 5.4-1060.835.78PVD
Fox Shox (Torco RSF Medium)- 31.82 9.573003090.73.32PVD
Torco RSF Medium (Purple)- 31.82 9.573003090.73.32PVD
Maxima Bicycle Fork Fluid (10wt)10 32.00 6.281511510.85.1PVD
Maxima Fork Oil (10wt)10 32.00 6.281511510.85.1PVD
Maxmima Racing Fork Fluid (165/150, 10 wt)10 32.00 6.281511510.85.1PVD
Spectro Fork Oil (10wt)10 32.80 5.61111070.835.86PVD
RaceTech (Motorex) (Medium US2)10 32.90 7.22001920.784.57PVD
Bel-Ray Fork Oil (10wt)10 33.00 5.91231230.825.59PVD
RockShox (10wt) (Torco 15)10 33.00 8.42402470.753.93PVD
Torco RFF 1515 33.00 8.42402470.753.93PVD
Shell Advance Fork 55 33.05 7.091851850.794.66PVD
Kayaba G10S10 33.20 5.71111110.835.82PVD
Yamaha (Suspension G10)- 33.20 -----PVD
Suzuki (Fork G10)- 33.30 -----PVD
White Power (7.5)7.5 33.43 -----PVD
Bel-Ray HVI (10wt)10 33.50 103063080.73.35PVD
PJ1 Fork Tuner (10wt)10 33.90 5.7-1060.835.95PVD
Kawasaki (Fork G10)10 33.90 -----PVD
Red Line D4 ATF- 34.00 7.51981970.784.53PVD
Mobil 1 Synthetic ATF- 34.00 7.61992020.784.47PVD
Silkolene Fork Oil (10wt)10 34.90 7.051691690.84.95PVD
Honda Pro HP Fork Oil (SS-47) (10 wt)10 35.20 ---0.59-PVD
Motul Fork Oil, Comfort (Medium 5-10)7.5 35.30 61151140.835.88PVD
Bardahl (10w Fork Oil)10 35.50 6.91581580.815.14PVD
Motorex Racing Fork Oil (7.5w)7.5 35.90 7.7190---PVD
Showa Suspension Fluid SS-08 (10wt) (Apollo)10 36.47 7.242001670.85.04PVD
Silkolene Pro RSF (7.5wt)7.5 37.00 123223390.683.08PVD
Maxima Racing Fork Fluid 165/150 (clear)10 37.40 7.72182--4.84Maxima
Maxima Fork Oil10 37.40 7.72182--4.84Maxima
Shell Advance Fork 1010 38.97 7.441611610.815.24PVD
Castrol Synthetic Fork Oil (10wt)10 42.00 7.51501470.825.6PVD
RockShox (15w Extra Heavy) (Torco 20)15 42.80 10.42502450.764.12PVD
Torco RFF 2020 42.80 10.42502450.764.12PVD
Agip Fork (10wt)10 45.00 8.31641620.825.42PVD
Elf Moto Fork Oil SYN (10)10 45.40 7.61351340.835.97PVD
Spectro Fork Oil (15wt)15 45.60 7.21191180.846.33PVD
Repsol Moto Horquillas Fork Oil (10W20)- 46.00 8.41501610.825.48PVD
Maxima Bicycle Fork Fluid (15wt)15 46.00 8.481541630.825.42PVD
Maxima Fork Oil (15wt)15 46.00 8.481541630.825.42PVD
Maxima Racing Fork Fluid (235/150, 15wt)15 46.00 8.481541630.825.42PVD
Castrol Fork Oil (15wt)15 46.50 8.31501550.825.6PVD
ELF Moto Fork Oil (10wt)10 47.00 8.31531530.825.66PVD
Maxima Racing Fork Fluid 235/150 (orange)15 47.10 8.94151--5.27Maxima
Maxima Fork Oil15 47.10 8.49151--5.55Maxima
Spectro, Golden Spectro (light)- 47.27 16.762353700.652.82PVD
Kayaba G15S15 47.30 7.21121120.856.57PVD
Yamaha (Suspension G15)15 47.30 -----PVD
Silkolene Pro RSF (10wt)10 47.36 13.693033030.713.46PVD
Suzuki (Fork G15)15 47.70 -----PVD
White Power (10)10 48.07 -----PVD
Silkolene Fork Oil (15wt)15 48.45 8.51531530.825.7PVD
Bel-Ray HVI (15wt)15 49.00 13.92972980.723.53PVD
Kawasaki (Fork G15)15 49.50 -----PVD
Motorex Racing Fork oil (10w)10 52.50 9.9170---PVD
Bel-Ray Fork Oil (15wt)15 53.00 7.51031030.867.07PVD
Red Line High Temp ATF- 53.90 101721760.815.39PVD
PJ1 Fork Tuner (15wt)15 55.30 8.7-1330.846.36PVD
Motul Fork Oil Factory Line (Heavy 15-20)- 61.00 13.22242250.784.62PVD
PJ1 Fork Tuner (20wt)20 61.70 8.4-1060.867.35PVD
Spectro Fork Oil (20wt)20 65.00 8.91101110.867.3PVD
Maxima Bicycle Fork Fluid (20wt)20 65.00 12.92012040.85.04PVD
Maxima Fork Oil (20wt)20 65.60 12.92012020.85.09PVD
Red Line (Heavy, orange)30 66.80 162562560.764.18PVD
Shell Advance Fork 1515 67.00 10.371201430.856.46PVD
Silkolene Fork Oil (20wt)20 67.70 8.751011010.877.74PVD
White Power (15)15 67.81 -----PVD
Castrol Fork Oil (20wt)20 68.00 11.21501590.846.07PVD
Repsol Moto Horquillas Fork Oil (15W30)- 68.00 11.21501590.846.07PVD
Agip Fork (15wt)15 69.00 11.51621630.836PVD
Motorex Racing Fork Oil (15w)15 69.80 12.8160---PVD
Maxima Fork Oil20 71.10 11.28151--6.30Maxima
Elf Moto Fork Oil (15)15 72.60 11.61551550.846.26PVD
Bel-Ray Fork Oil (20wt)20 73.50 9.51061070.877.74PVD
Motul Fork Oil - Comfort (Heavy 15-20)- 77.90 10.11111120.877.71PVD
Torco Synthetic RTF- 82.50 14.331821820.835.76PVD
Motorex Semi-Bath fork oil, 5W40- 90.90 14.61691680.846.23PVD
Silkolene Pro RSF (15wt)15 92.50 19.52352330.794.77PVD
ELF Moto Fork Oil (20)20 99.00 14.61501530.856.78PVD
Agip Fork (20wt)20 104.00 15.031551510.866.92PVD
Silkolene Fork Oil (30wt)30 105.00 11.841011020.898.87PVD
Bel-Ray Fork Oil (30wt)30 105.00 121041040.898.75PVD
Kayaba G30S30 116.10 16.71561560.866.95PVD
PJ1 Fork Tuner (30wt)30 116.90 15-1330.877.79PVD
Spectro, Golden American 4 (20w50)- 155.00 19.61461450.877.91PVD


Credit to the source: Most of this came from www.peterverdonedesigns.com