Question about Fox fork red/green oil
I have a Fox 32 Float 120 FIT RLC 15QR from 2011 (I believe), that has had the travel reduced by the original owner from 120mm to 100mm. I would like to return it to the original travel. I believe there's just a plastic spacer inside the fork, on the air spring assembly. I'm confident that I can disassemble the fork and remove the spacer by myself. (Not forgetting to put it back together as well )
My question is, however, what oils can I use to replace what's inside the fork now? There are no Fox dealers around where I live, nor would I like to order those terribly high-priced big containers of Fox fork oil for just this little job.
The manual says that I should use:
FOX Red 10 wt. - Damper - 30.4ml
FOX Green 10 wt. - Damper-side/Spring side oil bath - 30.0ml
FOX Float Fluid - Air Chamber - 5.0ml
Couldn't I just use any enduro etc. motorcycle 10wt. fork fluid instead of the Fox Red and Green stuff? If both oils are 10wt, then what's the difference between the two?
Also, what sort of oil is the Float Fluid, and can I use something else?
I understand that this has been asked many times and I've read the other threads, but there wasn't any major conclusion to this and they were talking about older forks.
Thanks in advance!
Last edited by Patuman; 07-03-2013 at 11:06 AM.
The red goes in the damper, the green goes in the legs so you just need the green 30ml each leg. Not sure about motorcycle oil etc but probably fine.
Float fluid is much thicker, its cheap for a 5ml pillow pack, just get one.
Motor oil has been recommended for the bath oil. I used it for a year in my Fox FIT fork and it worked well. It's a little thicker than Fox green oil and lubricates the stanchions well.
For the Float fluid, some people substitute 90w gear oil. I've always used float fluid.
The main differences between Fox 10wt Red and 10wt Green are the lubricity (how well it lubricates) and the viscosity index (how much the viscosity changes as the oil heats up). Oil "weight" is a silly measurement of viscosity as one brand's 10wt can be another's 5wt, the value you really need to know is the kinematic viscosity (measured in centistokes, or cSt) at 40 degrees celsius (one of the two standard temps for measuring viscosity, the other is 100C which is much hotter than fork dampers usually get). A good chart for comparing between brands can be found here: http://www.peterverdone.com/wiki/ima...osity-Data.gif
What it boils down to is this:
10wt Red is an excellent DAMPING fluid because of its high viscosity index. This makes it particularly suitable for rear shocks (which can run at surprisingly high temperatures) and low volume fork cartridges (Fox's FIT carts) because its viscosity does not change much as it heats up. This fluid is fine to replace with most other brands' equivalents, meaning ~47cSt @ 40C and a VI of 300+. However, it is not recommended as a bath oil, as its lubricity is not particularly amazing, so don't go putting it in your lowers.
10wt Green has a lower viscosity index than the Red, but has much better lubricity. This means that it is very slippery, and excellent for dampers with high volumes (such as open bath lowers requiring oils of this viscosity), or lubricating fork lowers (in fact, it's what I use in all fork lowers unless a particular open-bath damper requires a different viscosity fluid, such as Marzocchi dampers). There is no unit of measurement for lubricity, which means it's 100% trial and error to find something suitable. This makes the Green fluid harder to replace with other brands' alternatives, and I am yet to try any fluid that I have found to be slipperier. I would highly recommend using it where Fox say to.
As for Float fluid, I again recommend using only Float fluid and not a replacement, as its viscosity and constituency is not made known to the public, but it works exactly as it is intended to - it is a very good lubricant for air piston seals.
To summarise: you will have no problems subsituting the Red fluid with any other brand's equivalent high-VI oils with a comparable viscosity (again, around 47cSt), but the Green and the Float fluids are quite specialised and attempting to replace those is not something I would personally recommend. I realise they are expensive, but they are the right tool for the job.
Well that about sums it up. Fox recommends their oils for a reason. They are designed with a particular use in mind. Normal motor oil is cheaper but is designed with a different purpose in mind.
Originally Posted by Steve VS
Go with the fox. My .02
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