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Fox Fork Oil

canadmos

Cake Tease
May 29, 2011
10,293
6,354
Canaderp
Can one of you lube experts give me a hand?

I'm almost positive that my fork is needing its cartridge to be serviced or at least have its fluid changed. The thing is, around here it seems to be hard to find a place that is willing to actually order the Fox suspension fluid without trying to rape me at the same time.

I change the seals and the lower leg oil all the time, so I am fairly comfortable with opening this thing up. I just have no clue what type of fluid to buy. I went to a powersports store and found some Torco RFF 10 fluid that says "5.70cSt 260vi" on the bottle and it is a transparent and almost colourless fluid. It smells pretty decent too, but I have no comment on the taste. :shocked:

Would that be okay to put inside the cartridge? The store also had Bel-Ray 10wt fork oil in stock.

All I'm looking for is a replacement fluid that will act the same as the Fox Red 10wt, that I can easily find locally.

Thanks!
 

maxyedor

<b>TOOL PRO</b>
Oct 20, 2005
3,357
523
In the bathroom, fighting a battle
Any suspension oil is going to have the same characteristics as the Fox fluid. 10w motor oil will work, but lacks the additives that make Fox oil good for suspension.

Bel Ray is really good stuff, I'm sure torco is decent, but Bel Ray is what most MX riders are running.
 

canadmos

Cake Tease
May 29, 2011
10,293
6,354
Canaderp
Sounds good. Did I get the right stuff then? It has a big 10 on it, but it doesn't exactly say 10wt though..
 

Pesqueeb

bicycle in airplane hangar
Feb 2, 2007
28,945
4,638
Riding the baggage carousel.
You sure it doesn't say 10w instead of just 10? I'd assume you got the right stuff, this is the right stuff http://www.belray.com/bel-ray-high-performance-fork-oil

This would also be just fine http://www.belray.com/bel-ray-hvi-racing-suspension-fluid

Last time I rebuilt my F29, I used Bel Ray 10 that I had left over from rebuilding the front on my moto. I looked all over for equivalent ratings, a mil-spec, MSDS, etc but couldn't find very much useful info. I think it's the same thing and it sure looks the same, but I can't prove it. That said, both the BMW and the bicycle fork work and behave as advertised.
 

canadmos

Cake Tease
May 29, 2011
10,293
6,354
Canaderp
Just to follow up on this, I ended up going back and picking up the bottle of Bel Ray oil. I took the fork apart and it looks like the bladder inside of the cartridge somehow burped outside of the ring thingy that sits on top of it.

I ended up putting the Bel Ray oil inside of the damper as it is a dark green colour and I put the Torco fluid in the lower legs, which is an amber colour. I figure doing this is a smart idea as it will help to identify a leak in the cartridge if the two fluids mix and change colour.

Parking lot squish test says that the fork is buttery smooth now.
 

blindboxx2334

Turbo Monkey
Mar 19, 2013
1,347
100
Wets Coast
you mean the fit bladder? that thing was a b!tch to get seated properly when i was rebuilding my damper..

gah, i still need to buy oil for my lowers. damn fox shipping my 40 dry :mad:

edit:
not to derail this thread too much, but ive got red 10wt fluid already and someone said the green fox oil is better for being in the lowers (talking about my dry 40 here). should i go buy green fluid? or just use the red fluid instead?

i know you can put red fluid in place of green, but the one person who told me to use the green fluid works at a fairly reputable shop.. opinions?
 
Last edited:

Pesqueeb

bicycle in airplane hangar
Feb 2, 2007
28,945
4,638
Riding the baggage carousel.
you mean the fit bladder? that thing was a b!tch to get seated properly when i was rebuilding my damper..

gah, i still need to buy oil for my lowers. damn fox shipping my 40 dry :mad:

edit:
not to derail this thread too much, but ive got red 10wt fluid already and someone said the green fox oil is better for being in the lowers (talking about my dry 40 here). should i go buy green fluid? or just use the red fluid instead?

i know you can put red fluid in place of green, but the one person who told me to use the green fluid works at a fairly reputable shop.. opinions?
I suspect the color difference is mostly irrelevant, especially if both the red and green are by the same manufacturer. 10wt is 10wt is 10wt. That said, color might be a reflection on different additives to the oil, or a different chemical makeup of some kind.
 

kickstand

Turbo Monkey
Sep 18, 2009
3,445
392
Fenton, MI
I suspect the color difference is mostly irrelevant, especially if both the red and green are by the same manufacturer. 10wt is 10wt is 10wt. That said, color might be a reflection on different additives to the oil, or a different chemical makeup of some kind.
Fox makes both a red and green and does specify green for the lowers. That said, I know nothing of what makes oils and lubricants work properly, but I used what the manufacturer specifed due to my lack of knowledge.
 

Pesqueeb

bicycle in airplane hangar
Feb 2, 2007
28,945
4,638
Riding the baggage carousel.
According to this, all 10w is not the same.

http://www.peterverdone.com/wiki/index.php?title=Suspension_Fluid

I can't speak to the accuracy of any of this. I do know that I don't like to think hard so I just give up and overpay for the Fox fluid.

Edit: Removed outdated link

The way I read that, it is. I think the point they are making is that what constitutes "10wt" has a range that's too broad for fine tuning suspension. I'll buy that, seems to make sense.
 

herbman

Monkey
Feb 16, 2011
104
8
North West Tasmania
you mean the fit bladder? that thing was a b!tch to get seated properly when i was rebuilding my damper..

gah, i still need to buy oil for my lowers. damn fox shipping my 40 dry :mad:

edit:
not to derail this thread too much, but ive got red 10wt fluid already and someone said the green fox oil is better for being in the lowers (talking about my dry 40 here). should i go buy green fluid? or just use the red fluid instead?

i know you can put red fluid in place of green, but the one person who told me to use the green fluid works at a fairly reputable shop.. opinions?
I would not used red in the lowers, it does not seem to play nice wtih air and becomes sticky when used in open bath/fork lowers. But it is great in sealed cartridges where it is not in contact with air. It also doesn't thin out with high temps because of its high VI.
Fox red is made by another company, but I can't think of it now.

Green is great in lowers and seems to be a fox only product as there are no other oils on the market with the same specs.
It can be used in cartridges but has a lower VI and doesn't take heat as well as the red.
It is better than anything out there that I have tried in the lowers and is working great in the open bath damper in my 32s. Well worth the money IMOH.

The cSt is what you should be looking at when looking at oil weights, the the weight marked on bottles only seems the be a way for each company to rank there oils in their range and is not that flash when comparing other companies oils
 

Udi

RM Chief Ornithologist: “I Brake for Birds”
Mar 14, 2005
4,776
929
You really should post threads like this in the DH forum. I just stumbled across this on a random scan. Herbman is correct on all counts, apart from that there's some misinformation here.

To answer the questions:

- Stock damping fluid in Fox FIT carts is Fox Red 10wt (rebadged Silkolene Pro RSF 10wt), it has a kinematic viscosity of 47cSt and a VI of 303. 10wt fluids are definitely NOT all the same and there is no regulation to control viscosity let alone other factors like lubricity and viscosity index (temperature stability). These factors are particularly important in Fox forks where there are only small amounts of fluid dedicated to particular tasks within the fork.

- The Torco product linked earlier is way too thin to provide factory damping performance in a Fox FIT cartridge. The original viscosity is 47cSt (on the thick side for a 10wt oil) and should be maintained. Given the low oil volume, a high VI number (300+) is also important. Silkolene Pro RSF 10wt or a mixture of Redline oils (Medium and Heavy) will be the only commonly available alternatives. In this case the viscosity is the concern, 5.7 vs 47 = way too thin.

- Buy Fox Green oil for the lowers. Red is not designed for good sliding performance and thus will result in more stiction when used here. There are two specific products for a reason. As already suggested, the Green oil is a custom formulation (made by Torco, but not part of their lineup) thus there is no off-shelf replacement. If you live in the US it's cheap enough that you should just buy it. If you're overseas and it's too expensive, Motul Expert has reasonably good sliding performance, as do Torco fork fluids. Just try to match the viscosity in cSt - the Green oil is 47cSt also.

In summary - use Fox Red in the damper (or Silkolene Pro RSF 10), and Fox Green in the lowers. Deviating from these requires some very careful number/performance matching, there are very few suitable alternatives if you want to maintain factory performance.
 

canadmos

Cake Tease
May 29, 2011
10,293
6,354
Canaderp
Thanks for the information. I didn't put that Torco fluid in the damper, I used that for the lowers. So far with the BelRay oil in the damper it feels okay. Maybe a tad softer?

The problem I face here is that my local parts store only stocks Torco, BelRay and maybe Motorex oil. Perhaps not Motorex, I forget what the third line of oil was. And for them to order in anything, they will charge way too much. Same thing at bike stores.
 

trailbildr

Chimp
Aug 14, 2012
17
0
Maxima fork oils are very good. Push uses them. Suspension Experts use them. RockShox BlackBox guys use it. I use it because they use it.

Maxima has an analogue for everything that Fox, RockShox, Marz, Manitou, etc use. They are great with customer service too.

mk
 

trailbildr

Chimp
Aug 14, 2012
17
0
For Fox red or for Green?

Torco and Silkolene have analogues. For the Red stuff, it's the shock oil. The Fox Green is the fork oil.

http://www.maximausa.com/shopping/index.php?main_page=index&cPath=7

Basically, if you have air in the mix (like an open bath damper) then you need something that doesn't foam up. For FiT and rear shocks, there is no air in the mix so you can use dedicated damping fluid that doesn't have to deal with sloshing around. That's the simplest way I can explain it.

So Maxima shock fluid is for the damper (7wt) and Fork Oil (10wt) for the O/B dampers and for the lower leg lubrication. I may be off on those weights as I'm not in the shop staring at them right now, but them's the basics.

I have plenty of extra if you need some. I buy it by the case from Maxima. RockShox uses 5wt in the damper, 15w in for lower leg lube. Marz, Manitou and (gasp!) Lefty's use 7.5w. And Float fluid can be replaced by Mobil1 Synthetic 75w-90. Those are the analogues I can recall. Let me know if you need more specifics on other forks.

mk
 

Udi

RM Chief Ornithologist: “I Brake for Birds”
Mar 14, 2005
4,776
929
The Fox Green is NOT the Torco fork oil. It may be a reasonable substitute for lower lubrication in a pinch (on FIT forks), but won't have the correct viscosity for Fox O/B or O/C dampers.
Read post #16.

You can read the cSt@40 and VI values on the bottle of Green oil, they do not line up with any oils in the Torco product range, and the colour does not match either. This is a custom formulation made for Fox (by Torco) for the purposes of better sliding performance and there is no off-shelf replacement.

Fox Red however is identical to off-shelf Silkolene Pro RSF 10wt, and thus this can be used as a direct replacement. See my notes regarding viscosity in post #16, using 'any' shock oil like you suggest will result in a reduction of damping. I'd aim to match the 47cSt@40 viscosity with a VI >300. Blending Redline is an option to achieve this if you can't obtain Fox Red or Pro RSF.
 

trailbildr

Chimp
Aug 14, 2012
17
0
I don't have any Torco products. I guess I should have modified Torco and Silkolene with 'OR'.

Maxima is very helpful if you have specific questions about their formulations at least. I know that they have a version of Float Fluid coming out as well as Slick Honey, if it's not out already. They have a whole bike line of products they've been prepping to launch. I have some samples that I have yet to test out.

mk
 

GodSmack

Chimp
May 27, 2013
90
0
BC
My two cents. Any fork oil of a similar weight will work. More importantly if you have a FOX fork change the oil frequently and you will have butter smooth performance and longer lasting seals. I buy Bell Ray fork oil for 20 bucks a litre.
The Torco oil you pictured has a pic of a fork on it! Its ten weight oil! Relax your fork will like it.
 

jonKranked

Press Button, Receive Stupid
Nov 10, 2005
58,080
6,192
media blackout
My two cents. Any fork oil of a similar weight will work.
as Udi already pointed out, fork oil weight is unfortunately nearly useless, basically a guideline at best. what you really want to go by is cSt (centistoke) which is a measurement of viscosity.
 

GodSmack

Chimp
May 27, 2013
90
0
BC
A reduction of damping................. OK..........You people should buy that special optimized oil for your fork. Its realy expensive ........but its optimised.
Do you change your oil viscosity in the winter? . Temperature plays a huge role in oil viscosity. My fork felt harshly over damped last ride. It was minus 4 on my last ride.
Id say I should use 5 weight in the winter and 10 weight in the summer. Who the hell actualy changes the oil to match the season? Not me.
 

jonKranked

Press Button, Receive Stupid
Nov 10, 2005
58,080
6,192
media blackout
i'm gonna open a gas station and label the gases with the equivalent of oil "weight". the various octanes will be labeled:

-burny
-really burny
-extra burny
-super extra burny
 

GodSmack

Chimp
May 27, 2013
90
0
BC
i'm gonna open a gas station and label the gases with the equivalent of oil "weight". the various octanes will be labeled:

-burny
-really burny
-extra burny
-super extra burny
Octane is just a guideline on how burny your fuel is. British thermal units are much more accurate!
Still I believe the super extra burny fuel is optimized! :)
 

beneadragos

Chimp
Feb 12, 2014
1
0
Iasi
Very interesting and useful tips.I read step by step this informations and help me very much.Thank you very much for this informations!