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Fox 20wt gold oil?

slimshady

¡Mira, una ardilla!
@rockofullr
Yeah just try the mineral 15w40, let us know how it goes.

@Happymtb.fr
Try Motul Expert 10wt if you have problems with cold temps, I've used it myself with success. I think what they claim is entirely possible, especially since mineral oil bases are less temperature stable. I found under cold temperatures in Europe suspension would become sticky regardless of oil though until it warmed up over a run, maybe the 20w Gold is a bit worse and you could use it only in less cold seasons if you think it's a concern.
My two devaluated peso cents. Down here the Fox oil is harder to find than actual gold, so I resorted to use the 15W40 Elf semisynthetic remaining from the oil change of my Reanult Kangoo. Have been doing the same for almost a year now, with good results both on cold (2-3 celsius) and hot weather (37-38 celsius).
 
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Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
resorted to use the 15W40 Elf semisynthetic remaining from the oil change of my Reanult Kangoo. Have been doing the same for almost a year now, with good results both on cold and hot weather.
Great minds think alike...

Funnily enough I've been dropping the same 15w40 in my Renault (rs172) as well, it positively hates it and hates me for putting it in there since factory spec is 5w40 and cold seasons are better on 0w40. Always had dreams of dropping the F4R engine in a Kangoo. :D
 

slimshady

¡Mira, una ardilla!
Great minds think alike...

Funnily enough I've been dropping the same 15w40 in my Renault (rs172) as well, it positively hates it and hates me for putting it in there since factory spec is 5w40 and cold seasons are better on 0w40. Always had dreams of dropping the F4R engine in a Kangoo. :D
Prepare to add a couple of training wheels to the sides of the Kangoo. It's pretty easy to drive It near the tumbling point when taking a turn too fast :dance:.

Anyway, I have always preferred semisynthetic oil for lubrication to pure mineral. It's stickier when needed and slippery enough to keep stuff sliding properly.
 

Udi

RM Chief Ornithologist
Mar 14, 2005
4,915
1,200
Do you have any idea about why Fox doesn't recommend the Gold oil to be used in their air chamber?
It's purpose is purely for reducing friction on the alloy stanchion / polymer bushing interface. It's also very tacky and it's possible Fox have concerns about it clogging EQ valves or something like that in the air spring. For reference I've also heard some service centers don't use it on smaller air forks (for lower lube oil) as it has a tendency to migrate into the dampers and air chambers. I've personally found it good on my 40 and 36 but both are converted to coil and have larger volume than smaller 32/34 forks.

Anyway, I have always preferred semisynthetic oil for lubrication to pure mineral. It's stickier when needed and slippery enough to keep stuff sliding properly.
None of the oils I've suggested here are technically pure mineral anyway, and "synthetic" can mean a whole bunch of things from Group III hydrocracked mineral oils to Group IV/V PAO and ester oils. In all cases it refers only to the base oil. Both motor oils and suspension fluids are much more than just a base oil - the actual sliding performance tends to have more to do with the additive package, particularly in the application of an anodized tube sliding linearly in a teflon/polymer coated bushing. This application is quite different to both a combustion engine and a suspension damper.

Because of this it's hard to make generalisations without knowing the additive package (one semi-synth 15w40 could be very different from another), and it's also tricky to make recommendations without testing two fluids back to back.

With that said, it is pretty easy to try different fluids experimentally, and these days most forks slide pretty well anyway so fluid choice isn't so critical. The only thing to note is that the polymer coating on the bushings can be sensitive to various oil additives and in rare cases can cause slight swelling and increase friction - however Fox bushings are less sensitive than RS in my experience.
 

slimshady

¡Mira, una ardilla!
It's purpose is purely for reducing friction on the alloy stanchion / polymer bushing interface. It's also very tacky and it's possible Fox have concerns about it clogging EQ valves or something like that in the air spring. For reference I've also heard some service centers don't use it on smaller air forks (for lower lube oil) as it has a tendency to migrate into the dampers and air chambers. I've personally found it good on my 40 and 36 but both are converted to coil and have larger volume than smaller 32/34 forks.


None of the oils I've suggested here are technically pure mineral anyway, and "synthetic" can mean a whole bunch of things from Group III hydrocracked mineral oils to Group IV/V PAO and ester oils. In all cases it refers only to the base oil. Both motor oils and suspension fluids are much more than just a base oil - the actual sliding performance tends to have more to do with the additive package, particularly in the application of an anodized tube sliding linearly in a teflon/polymer coated bushing. This application is quite different to both a combustion engine and a suspension damper.

Because of this it's hard to make generalisations without knowing the additive package (one semi-synth 15w40 could be very different from another), and it's also tricky to make recommendations without testing two fluids back to back.

With that said, it is pretty easy to try different fluids experimentally, and these days most forks slide pretty well anyway so fluid choice isn't so critical. The only thing to note is that the polymer coating on the bushings can be sensitive to various oil additives and in rare cases can cause slight swelling and increase friction - however Fox bushings are less sensitive than RS in my experience.
Re: Fox vs RS. I concur. For Marzocchi and RS products I normally use Motorex oils, pretty easy to find here in Argentina. Since Fox started marketing the 20wt stuff (and I got a Fox fork) I started using the Elf stuff in It.

I knew oil classifications were as subjective and brand dependant as they could be, but as you said it's a trivial thing to try different brands/compositions and even to make your own blend.
 

Flo33

Turbo Monkey
Mar 3, 2015
2,057
1,298
Styria
I've personally found it good on my 40 and 36 but both are converted to coil and have larger volume than smaller 32/34 forks.
May I ask what year and model your converted 36 is? I run a Frankensix myself and am considering converting it into a Vanilla too. It was born a 2006 110-150 mm TALAS RC2, became a PUSHed TALAS 36 with new lowers in 2009, a 160 mm FLOAT with steel neg spring in 2013 and recently received a 2015 RC2 cartridge upgrade.
I'm struggling to find the correct spring shaft for my abomination to fit a steel or even better Ti spring.
 

rockofullr

confused
Jun 11, 2009
7,342
924
East Bay, Cali
Ended up using this stuff. Worked fine for a day of lift riding in the Tahoe dust. Should be getting Fox oil in this week so I won't be doing a long term test.

 
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cwrender

Chimp
Sep 30, 2008
11
4
I found Fox Gold only to be usable in temperatures over 10°C. If you are having problems with stiction in cold temperatures try Mobile Vactra no.1 (tested by me between -5°C and 30°C). If your temperatures are above 5-7°C Mobile Vactra No.2 could be the better choice. So when Supertackys start working take No.2, if colder use No1.
 

Happymtb.fr

Turbo Monkey
Feb 9, 2016
1,907
1,252
SWE
Very strange that you get different colour for different legs... where did the green stuff come from? Damper or spring side?
 

mrgto

Monkey
Aug 4, 2009
295
118
If you want the gold oil call Fox and they will ship you a quart for way cheaper than I could find at the LBS or online store. I ordered 5 crush washers for each side of my fork while I was at it to have when doing lower services.