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Fork oil discussion - brands, cold temps

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10/18/2019 9:18 AM

Time for me to service my DVO Onyx sc damper and lower, and do a basic air can service for my SuperDeluxeAlanche.

What suspension oil is has good lube properties, easily available, and not stratospheric price?

Also thinking of going slightly lighter weights so they feel good in PNW winters where we're usually riding in 30's and 40's. DVO just says 7.5 weight in lowers, 2.5 in damper. Maybe that's light enough that good oil will feel fine in winter? Fox gold 20 always felt a bit sludgy in cold, but that's pretty heavy oil so the 7.5wt might play nicer in cold?

I heard on a PodCast, maybe the Darrin Murphy/Push one about some brand of oil that has great lubricity. Can't recall, and a quick scan through that podcast.

I'm probably overthinking this...

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10/18/2019 9:50 AM

JVP wrote:

Time for me to service my DVO Onyx sc damper and lower, and do a basic air can service for my SuperDeluxeAlanche.

What suspension oil is has good lube properties, easily available, and not stratospheric price?

Also thinking of going slightly lighter weights so they feel good in PNW winters where we're usually riding in 30's and 40's. DVO just says 7.5 weight in lowers, 2.5 in damper. Maybe that's light enough that good oil will feel fine in winter? Fox gold 20 always felt a bit sludgy in cold, but that's pretty heavy oil so the 7.5wt might play nicer in cold?

I heard on a PodCast, maybe the Darrin Murphy/Push one about some brand of oil that has great lubricity. Can't recall, and a quick scan through that podcast.

I'm probably overthinking this...

Good question, and yeah, you probably are overthinking it to a degree. Once you are riding hard your fork oil will warm up a bit, too.

One thing to note, according to the suspension nerds in moto, 2.5 and 5wt are going to act very similar in a fork. They may be different on paper, but on that side of things, a lot of people can't even tell the difference.

What I'd do if I were you is just use something a bit lighter when you do a rebuild. As far as Darren and his special fork oil, don't forget he's got a business wink (not knocking him, just saying out of the numerous fork oils I've tried I can't tell too much a difference)

That was a lot of typing to just say "run what you brung"

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10/19/2019 2:31 AM

I use Maxima fork oil. Half the price of the "bicycle specific" stuff and I doubt I would be able to ever tell the difference.

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10/21/2019 3:06 PM

Well Maxima is the one brand that DVO says NOT to use. Seal swellers or something.

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Abit Gear: great fitting Enduro MTB shorts in Slim Fit and Athletic Fit.

10/21/2019 4:23 PM

JVP wrote:

Well Maxima is the one brand that DVO says NOT to use. Seal swellers or something.

Good thing you double checked man.

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10/21/2019 4:41 PM

It’s the Moto fork oil that has the extra additives the bicycle specific doesn’t, should be fine and is used a lot around the shop I’m at.

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10/21/2019 4:45 PM

Push use Motorex 5wt for fork dampers like the HC97 kit, they also do a good 2.5/3wt. the viscosity won't have a huge effect in either of your dampers so use the same at both ends and whatever quality brand is cheap/easily available to you. WPL is my favourite and is nice and slippery, their 2.5 or 5wt goes well in the Onyx damper

As for lowers, that is where something lighter than the usual 20wt will have an impact, so a 10wt or maybe lighter is good. To save money you could use WPL or Motorex 5wt for everything.

In short - 2.5 for the dampers and 10 for the lowers, or 5wt all round

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10/22/2019 6:12 AM

I use red line suspension fluids in my DVO forks and shocks. I think DVO used Driven SHX in fork dampers and spectro in the lowers.

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10/22/2019 9:41 AM

JVP wrote:

Well Maxima is the one brand that DVO says NOT to use. Seal swellers or something.

All the RockShox Ultimate forks now use Maxima Plush Fluid, choosing it over their own RS-branded suspension fluid.

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10/23/2019 2:20 PM

JVP wrote:

Well Maxima is the one brand that DVO says NOT to use. Seal swellers or something.

Verbl Kint wrote:

All the RockShox Ultimate forks now use Maxima Plush Fluid, choosing it over their own RS-branded suspension fluid.

Which was just Maxima fluid with RS branding.

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10/23/2019 2:31 PM

Maxima always made Rockshox's own fluid but it is different to the "plush" range, that's one of the concerns DVO has with Maxima fluid - they make so many different blends for people and some of them have been seen to react badly in DVO forks so they advise to stay away in general

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10/23/2019 4:10 PM
Edited Date/Time: 10/24/2019 11:37 AM

While a fluid change can help a little, the additional friction due to seals and o-rings shrinking is the real issue when it comes to poor fork performance in the cold.

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10/24/2019 7:39 AM

bturman wrote:

While a fluid change can help a little, the additional friction due to seals and o-rings shrinking is the real issue when it comes to poor fork performance in the cold.

Wouldn't the friction of riding warm things up to the degree this is less an issue? Any thoughts on what the catalyst to poor performance in super hot temps might be? Quad ring expansion?

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10/24/2019 8:16 AM

bturman wrote:

While a fluid change can help a little, the additional friction due to seals and o-rings shrinking is the real issue when it comes to poor fork performance in the cold.

jeff.brines wrote:

Wouldn't the friction of riding warm things up to the degree this is less an issue? Any thoughts on what the catalyst to poor performance in super hot temps might be? Quad ring expansion?

I'd recommend using the uh recommended fluids for whatever suspension you have.

We do seal compatibility testing with the fluids and can only guarantee the stock fluid won't swell or shrink the seals. Different suspension fluids from the same company (Maxima for example) might cause seal swell issues... don't know we haven't tested everything out there.


Poor performance in super hot temps is probably in your head (heat stroke haha)... and maybe slightly higher air pressure in the shocks. Dampers pretty much perform the same from 50f-150f (within a few lbf).

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10/24/2019 9:51 AM

Dave_Camp wrote:

I'd recommend using the uh recommended fluids for whatever suspension you have.

We do seal compatibility testing with the fluids and can only guarantee the stock fluid won't swell or shrink the seals. Different suspension fluids from the same company (Maxima for example) might cause seal swell issues... don't know we haven't tested everything out there.


Poor performance in super hot temps is probably in your head (heat stroke haha)... and maybe slightly higher air pressure in the shocks. Dampers pretty much perform the same from 50f-150f (within a few lbf).

Who's "we", sounds like you're with a mfr or something.

I think we all know just doing maintenance on your lowers is what really matters, but hey, why not nerd out a bit when it's dumping rain outside!

https://www.vitalmtb.com/features/MTB-Suspension-Q-amp-A-Session-Darren-Murphy-of-PUSH-Industries-on-The-Inside-Line-Podcast,2748
I finally found that podcast with Darren at Push, turns out it's Part 2. At the very end he says they did testing and found the Motorex with 3D tested nicely. Good enough for me.

Weirdly DVO doesn't spec what brand to use, just say "not Maxima". Them being a bit more specific would make life easier, but I had fun going down this rabbit hole.

I do find Fox 20wt does feel thick when it's freezing out, seems to struggle to get up into the bushings. But could just be in my head since like Brandon says, forks generally feel like poo in the cold no matter what. DVO recommended 7.5wt going into lower - nice and light either way.

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Abit Gear: great fitting Enduro MTB shorts in Slim Fit and Athletic Fit.

10/24/2019 10:08 AM
Edited Date/Time: 10/24/2019 10:09 AM

JVP wrote:

Who's "we", sounds like you're with a mfr or something.

I think we all know just doing maintenance on your lowers is what really matters, but hey, why not nerd out a bit when it's dumping rain outside!

https://www.vitalmtb.com/features/MTB-Suspension-Q-amp-A-Session-Darren-Murphy-of-PUSH-Industries-on-The-Inside-Line-Podcast,2748
I finally found that podcast with Darren at Push, turns out it's Part 2. At the very end he says they did testing and found the Motorex with 3D tested nicely. Good enough for me.

Weirdly DVO doesn't spec what brand to use, just say "not Maxima". Them being a bit more specific would make life easier, but I had fun going down this rabbit hole.

I do find Fox 20wt does feel thick when it's freezing out, seems to struggle to get up into the bushings. But could just be in my head since like Brandon says, forks generally feel like poo in the cold no matter what. DVO recommended 7.5wt going into lower - nice and light either way.

David is a senior suspension engineer at RockShox. He's also one of the fastest dudes in the States - pro podium contender at the BME level.


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10/30/2019 2:54 PM

JVP wrote:

Time for me to service my DVO Onyx sc damper and lower, and do a basic air can service for my SuperDeluxeAlanche.

What suspension oil is has good lube properties, easily available, and not stratospheric price?

Also thinking of going slightly lighter weights so they feel good in PNW winters where we're usually riding in 30's and 40's. DVO just says 7.5 weight in lowers, 2.5 in damper. Maybe that's light enough that good oil will feel fine in winter? Fox gold 20 always felt a bit sludgy in cold, but that's pretty heavy oil so the 7.5wt might play nicer in cold?

I heard on a PodCast, maybe the Darrin Murphy/Push one about some brand of oil that has great lubricity. Can't recall, and a quick scan through that podcast.

I'm probably overthinking this...

jeff.brines wrote:

Good question, and yeah, you probably are overthinking it to a degree. Once you are riding hard your fork oil will warm up a bit, too.

One thing to note, according to the suspension nerds in moto, 2.5 and 5wt are going to act very similar in a fork. They may be different on paper, but on that side of things, a lot of people can't even tell the difference.

What I'd do if I were you is just use something a bit lighter when you do a rebuild. As far as Darren and his special fork oil, don't forget he's got a business wink (not knocking him, just saying out of the numerous fork oils I've tried I can't tell too much a difference)

That was a lot of typing to just say "run what you brung"

When I worked for an oil company, they said the degree of precision they could achieve when making viscosities of oil rested at around 5 centistokes on the scale. Therefore, the odds of getting a "true" 2.5 are very bad. Your typical 2.5 Wt oil might be a 0 or 5 Wt anyway.
Not only might most riders not notice the difference, but the differences may be incorrect based on the label. Take that for what it's worth.

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10/30/2019 5:03 PM

Oh yeah, while they don't specify it, DVO does actually use WPL for their in-house "premium" service

I'm mostly of the opinion that changes in air spring (and IFP) temps increase or decrease the spring force more than damping changes. Below around 10*c the lower lube can make a big difference though.

As for seals, getting hot makes them larger (more squeeze) but also softer while cold temps makes them harder but smaller. I'm not sure which change is larger but its also tricky to separate that change from any change in the lubricants used on them.

I did a Temp test on the dyno recently with a Fox Boost valve shock, and curiously enough the overall damping actually increased as temperatures got higher due to the increased pressure acting on the boost valve!

I got a new temperature sensor for my Data logger this week so I'll be getting proper data on the subject in the future too

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