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  1. #1
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    Fork Oil Viscosity Chart, ignore the weight on the label.

    Owning two highly-tunable Foes F1-XL forks I've become a bit of a fork tuner, so I thought I'd share some oil viscosity info with you DIY guys. You can't just grab a bottle of X-weight oil and actually get what you want, since the manufacturers are all over the map when it comes to weights. So I built a chart of viscosities for several of the major brands:

    [SIZE="4"]Chart of fork oil viscosity.[/SIZE]

    If anyone has any additional oil specification data, please pass it along and I'll add it to the chart.
    Last edited by 1000-oaks; 03-10-2008 at 03:27 PM.
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  2. #2
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    Quote Originally Posted by 1000-oaks
    Owning two highly-tunable Foes F1-XL forks I've become a bit of a fork tuner, so I thought I'd share some viscosity info for other DIY guys. You really can't just grab a bottle of X-weight oil and get what you want, since the manufacturers are all over the map when it comes to weights. So here's a chart of viscosities for a few of the major brands.








    Brand

    Redline

    Redline

    Torco RFF

    Golden Spectro

    Torco RFF

    Maxima

    Redline

    Torco RFF

    Silkolene

    Golden Spectro

    Redline

    Fox Fluid

    Silkolene

    Torco RFF

    Maxima

    Torco RFF

    Silkolene

    Maxima

    Redline

    Silkolene

    Maxima
    Labeled Weight

    Like Water (1.4)

    ExtraLight (2.5)

    5

    Ultra Light 85/125

    7

    5

    LightWeight (5)

    10

    5

    Very Light 125/150

    Medium (10)

    7

    10W-20

    15

    10

    20

    15W-20

    15

    Heavy (15/20)

    20W-20

    20
    Viscosity at 40C in cSt

    5.5

    9.8

    10.75

    16

    16.1

    16.2

    18.4

    19.9

    22

    26.1

    30.4

    31.82

    32

    33

    37.4

    43.9

    46

    47.1

    66.8

    68

    71.1

    Viscosity Index

    344

    402

    ?

    ?

    ?

    202

    407

    ?

    106

    ?

    369

    300

    169

    ?

    182

    ?

    153

    151

    256

    101

    151



    The viscosity index reflects how well an oil retains its viscosity at various temperatures, so the higher the index the better. For some reason Torco seems to label their oil at double the weight it really is. (RockShox oil is alledgedly repackaged Torco but with the correct weight on the label.)
    I use the information from this site:

    http://www.peterverdonedesigns.com/bikesuspension.htm

    Fox uses Torco RSF not RFF.

  3. #3
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    Thanks for the catch on the Fox fluid, I just corrected it on my chart. (I'll keep updating and adding to the oil data page on my site, easier that way.)

    Peter Verdone's site where I found some of the information in my chart, great info.
    Craig Kelly is my copilot.Product Marketing and Product Photographer

  4. #4
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    Thanks! Good stuff.

  5. #5
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    There are quite a few discrepancies between your list and the http://www.pvdwiki.com/index.php?title=Suspension_Fluid list. I've just spot checked the Silkolene figures (non-Pro RSF).

    Where did your figures come from for each product?

    Potentially, this data or the pvd data could be misinformation. Potentially worse than no information at all.

  6. #6
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    I just completely redid the list (and made it a printable size), and many of the figures I pulled off manufacturers spec sheets conflicted with the pvd data. Personally I'm leaning toward the manufacturer's data, and will continue updating the list.
    Craig Kelly is my copilot.Product Marketing and Product Photographer

  7. #7
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    Quote Originally Posted by 1000-oaks
    I just completely redid the list (and made it a printable size), and many of the figures I pulled off manufacturers spec sheets conflicted with the pvd data. Personally I'm leaning toward the manufacturer's data, and will continue updating the list.
    Excellent. I'm struggling with one oil that I use because the manufacturer appears to have pulled the spec sheet because it is a discontinued product. The ideal job would be to maintain the list with hyperlinks to the manufacturers spec sheets.

  8. #8
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    Atf?

    Interesting chart. What's the viscocity weight of ATF? (maybe each brand is different, but is there a short range of real weights?)

    Back in the late '90's or Y2K there was an MTBR shocks-forum trend I followed of using ATF (auto-transmission fluid) instead of Marzocchi oil, rumored to be Golden-Spectro 7.5 wt, in their Z1 forks. ATF was rumored to have better anti-foaming properties than fork oil, and a $1.50 quart bottle of ATF was of course much cheaper than $20 for a pint of Marzocchi's oil. Compared to the Marzocchi "7.5 wt" I found I had to increase the Z1 fork damper aduster in slighlty towards the firmer direction to keep the same damping feel after changing to ATF.

    ATF was rumored to be 10wt but it acted like it was lighter than the Marzocchi oil's "7.5 wt". Maybe ATF is really close to 10wt but Marzocchi's fork oil is really much heavier at 26.1 wt as you list.

    Thanks for posting all the research.

  9. #9
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    I gotta hang it up for the night, still need to go though page two again.
    Craig Kelly is my copilot.Product Marketing and Product Photographer

  10. #10
    "El Whatever"
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    Quote Originally Posted by derby
    ATF was rumored to have better anti-foaming properties than fork oil, and a $1.50 quart bottle of ATF was of course much cheaper than $20 for a pint of Marzocchi's oil. Compared to the Marzocchi "7.5 wt" I found I had to increase the Z1 fork damper aduster in slighlty towards the firmer direction to keep the same damping feel after changing to ATF.

    ATF was rumored to be 10wt but it acted like it was lighter than the Marzocchi oil's "7.5 wt". Maybe ATF is really close to 10wt but Marzocchi's fork oil is really much heavier at 26.1 wt as you list.

    Thanks for posting all the research.
    I'm not sure about that, Ray.

    To top up the oil in my old auto tranny and to add oil to forks, I pull the oil from the bottle with a syringe and piece of tubing.

    I don't know how scientific is this, but I see that the ATF foams in the syringe while the Fork fluid (Yamalube, Motul, Fox, Zoke) doesn't while you suck it from the bottle.

    Maybe that's why it felt like being lighter than Zoke oil... because it was foaming.
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  11. #11
    I-S
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    I used Amsoil ATF in one pair of forks - It's 40C viscosity is 32.4. However, it seems thinner at low temps than other ATFs because it is fully synthetic. Esso Dexron III fluid is 37.

    The forks where I used the amsoil called for an SAE 20 fluid, but I wanted to increase the speed of compression and the ATF was about right.

  12. #12
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    Quote Originally Posted by Warp
    I'm not sure about that, Ray.

    To top up the oil in my old auto tranny and to add oil to forks, I pull the oil from the bottle with a syringe and piece of tubing.

    I don't know how scientific is this, but I see that the ATF foams in the syringe while the Fork fluid (Yamalube, Motul, Fox, Zoke) doesn't while you suck it from the bottle.

    Maybe that's why it felt like being lighter than Zoke oil... because it was foaming.
    Could be. I joked back then those early Z1 orifice damper forks must have used increased foaming at higher speeds to avoid spiking. Maybe that was really true!

  13. #13
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    I thought this would be a good thread to bump. Maxima seem's to be boasting some good index numbers.
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  14. #14
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    bump so i can find this easier the next time i need it...

  15. #15
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    Quote Originally Posted by Warp
    I'm not sure about that, Ray.

    To top up the oil in my old auto tranny and to add oil to forks, I pull the oil from the bottle with a syringe and piece of tubing.

    I don't know how scientific is this, but I see that the ATF foams in the syringe while the Fork fluid (Yamalube, Motul, Fox, Zoke) doesn't while you suck it from the bottle.

    Maybe that's why it felt like being lighter than Zoke oil... because it was foaming.
    Were you drawing the atf at operating temps and pressures it was designed for?

  16. #16
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    I've noticed some of PVD's numbers are off, for example, PJ1. I'd like to someone get PVD's chart in Excel so I can fix it, but I haven't found anything capable of OCRing it yet.

  17. #17
    "El Whatever"
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    Quote Originally Posted by junktrunk
    Were you drawing the atf at operating temps and pressures it was designed for?
    Good point... no.

    I was just sucking it with a syringe at atm pressure and ambient temp. Much like it would work on a bike fork.

    ATF in the car indeed would run hotter and pressurized by the pump.
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  18. #18
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    Excellent information. Thanks for everyone's time on this.

    urmb

  19. #19
    pvd
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    Hey folks,

    My chart was made a long time ago. Some of the products may have changed.
    If you have info that needs correcting, please send me that and I'll update my stuff. Include pds if you can.
    BTW, just use Red Line. It's really the best for tuning.

    Suspension Fluid - Pvdwiki

    http://www.peterverdone.com/wiki/ima..._Mix_Chart.pdf

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