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No Fear
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Discussion Starter · #1 ·
My question is simple

if we mix two bottle of the same brand same formula fluids / in my case sram pit stop 10 WT & 2.5 WT do we get a fluid with same characteristics but with a median viscosity ???

For example if we mix 10WT & 2.5 WT 50%50% do we get 6.25 WT ??


And if we want to make 5 Wt out of them how should we calculate the percentages ??

Thank you all very much....
 

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No Fear
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Discussion Starter · #2 ·
If mixxing 50 % 50 % of 10 & 2.5 makes 6.25

And ithink we want to get 5 Wt should we use more 2.5 right ?

You know these kind of questions never come to mind of someone living here he can access any thing he wants but here in iran some some times we are forced to use our mind and creation to overcome & solve mechanical problems

5 Wt fluid is so scarce and we have plenty of 10 & 2.5 left i want to find out if i can make 5Wt out of them
Are these calculations right ?

the left column indicates the offset from 50/50 that means

15% offset means to use 35% 10Wt & 65% 2.5 Wt

Text Colorfulness White Line Style
 

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No Fear
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Discussion Starter · #4 ·
It not a simple linear relationship, though linear may be close enough for this application. IDK the theory behind it but there are calculators and info you can find easily by googling "mixing viscocity".

Here's one:

https://www.widman.biz/English/Calculators/Mixtures.html
Thanx a lot Lone Ranger......

i dont know any thing about the CST unit i searched about its conversion to Wt.

But didnt came to a conclusion approximately i thunk

10 Wt = 100 Cst
2.5 Wt = ??? didnt find any thing on that
any body knows or have any info about Wt to Cst convertion ?

Thanx Again
 

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10 Wt = 100 Cst
2.5 Wt = ??? didnt find any thing on that
any body knows or have any info about Wt to Cst convertion ?

Thanx Again
There is no such thing as a cSt to Wt conversion. Stokes (usualy centi-Stokes or cSt) is the SI unit for kinematic viscosity and such measurements are only valid at a given temperature. Wt is non-standard and really only useful for comparisons within the same product line.

What products are you using? Someone might know the actual cSt values.
 

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Thanx a lot Lone Ranger......

i dont know any thing about the CST unit i searched about its conversion to Wt.

But didnt came to a conclusion approximately i thunk

10 Wt = 100 Cst
2.5 Wt = ??? didnt find any thing on that
any body knows or have any info about Wt to Cst convertion ?

Thanx Again
Unfortunately there is no standard I have been able to find for suspension oil wt. They are all over the place.
For engine oils, gear oils etc there are specific cSt ranges at specific temperatures. I can find nothing for suspension fluids and I've spent significant time looking.

10wt can be anywhere from 30cSt (redline) to 53 cSt (Motorex before 2015) at 40C.
 

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My question is simple

if we mix two bottle of the same brand same formula fluids / in my case sram pit stop 10 WT & 2.5 WT do we get a fluid with same characteristics but with a median viscosity ???

For example if we mix 10WT & 2.5 WT 50%50% do we get 6.25 WT ??

And if we want to make 5 Wt out of them how should we calculate the percentages ??

Thank you all very much....
Yes you can mix if you stay withing the brand as their weights are usually defined the same way.
As said before there is no CST to WT conversion.
 

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No Fear
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Discussion Starter · #12 ·
There is no such thing as a cSt to Wt conversion. Stokes (usualy centi-Stokes or cSt) is the SI unit for kinematic viscosity and such measurements are only valid at a given temperature. Wt is non-standard and really only useful for comparisons within the same product line.

What products are you using? Someone might know the actual cSt values.
Im using Sram pit Stop fluids

Liquid Product Fluid Red Floor


You don't really need to Home brew your own oils. If you have 2.5wt, use that for your damper as is, and buy a quart of motor oil for leg lube.
2.5 is ay too thin for a damper for a damper i think i always use 5 Wt for fork dampers

And as for the reason i am forced to home brew my own oil i mentioned where im living and the difficulties we have here

https://radtechnik.awiki.org/forkoil.html

@x-rated made a compilation of the cst of different oils at different temperatures. Scroll to see the sheet.
Every manufacturer has the data on their website.

Be careful when experimenting with lighter oil in the rear shock, it might end OTB.
Thanx a lot and also thanx a lot to all the other members who helped and gave info.........

cheers....
 

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On most modern shim based dampers, 2.5 feels a lot like 5wt! Unless your adjusters are already near maxed out and still fast, 2.5 is a viable substitute for 5wt, especially when availability is an issue.

RS 2.5 is 10.75 [email protected] But! VI is 325, so its pretty stable.
RS 5 is 16.1 cs[email protected] VI 285.
RS 10wt is 33 [email protected] but its also a different type of fluid, its more of a leg lube than a damper oil. VI is 240.

So while technically you can mix 2.5 and 10 to get a thickness similar to 5wt, the VI (viscosity index) will be wonky and the additive package might not be ideal for damping.

I should have expanded on the 2.5 recommendation more, but I do believe its better to just pour in the 2.5 than to try to mix it with 10, all things considered. 5wt isnt really *that* much thicker anyway, when you factor in the lower VI and all.
 

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On most modern shim based dampers, 2.5 feels a lot like 5wt! Unless your adjusters are already near maxed out and still fast, 2.5 is a viable substitute for 5wt, especially when availability is an issue.

RS 2.5 is 10.75 [email protected] But! VI is 325, so its pretty stable.
RS 5 is 16.1 [email protected] VI 285.
RS 10wt is 33 [email protected] but its also a different type of fluid, its more of a leg lube than a damper oil. VI is 240.

So while technically you can mix 2.5 and 10 to get a thickness similar to 5wt, the VI (viscosity index) will be wonky and the additive package might not be ideal for damping.

I should have expanded on the 2.5 recommendation more, but I do believe its better to just pour in the 2.5 than to try to mix it with 10, all things considered. 5wt isnt really *that* much thicker anyway, when you factor in the lower VI and all.
Where did you find the SRAM viscosities? I've got 272 suspension fluids listed but no official source for the SRAM fluids to verify them.

Your numbers match Torco specs, but those are the same bottles as Maxima.
 

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PVD's site lists them, and another one does too... but that might be based on the assumption that its rebottled torco.

Not official data. I didnt even check with sram.
Yeah the PVD stuff is quite old now. Rockshox moved to Maxima and seem to have maintained some sort of parity with the thinner fluids.

I've measured RS 5wt at almost exactly the same as Motorex 4wt from 0C-40C. I haven't seen the 10wt and don't have any reason to buy any to test.
 

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Thanx a lot too all the people who helped and shared their experiences .....

I think if i mix the 10 Wt & 2.5 Wt 50/50 % and get a 6.25 that would be near enough to 5 Wt to use this mixture as 5 Wt Isnt it ?
I'd just use the 2.5wt for damper and 10wt for bushing lube.

Shim stack dampers don't care about viscosity much and thinner is better as it gives less temperature variation and less uncontrolled damping from ports.
 

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Thanx a lot too all the people who helped and shared their experiences .....

I think if i mix the 10 Wt & 2.5 Wt 50/50 % and get a 6.25 that would be near enough to 5 Wt to use this mixture as 5 Wt Isnt it ?
You wouldnt get a 6.25wt fluid, thats sort of what I was trying to get at. You'd get a mix of two fluids with sort of unknown specs, somewhere between the two you mixed. They have different additives and different viscosity indexes.

It would work though. It wouldnt be 5wt, but that doesnt really matter either. If it would make you feel more confident in doing so, you certainly can mix them 50/50 and call it good. It is good enough... its just not 6.25wt.
 

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No Fear
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Discussion Starter · #20 ·
I'd just use the 2.5wt for damper and 10wt for bushing lube.

Shim stack dampers don't care about viscosity much and thinner is better as it gives less temperature variation and less uncontrolled damping from ports.
As im an Agile person ...........i saw this post too late...... i mixed 6 Bottles of them.........:eek:ut:

For the casing & bushings i only Use Red rum Actually the only person to have Red rum in iran you know a guy had imported them and nobody knew what they were used for

Some mechanics poured them into dampers and you know itss like puting grease inside the damper.......:lol:

people here dont pay much attention to gathering information about the job their doing......

I have an album of shits and awful mechanic jobs some so called mechanics do here

https://www.pinkbike.com/u/saber-mtb-shop/album/Shitty-Mechanics/

Its not recommended to look at them for obsessed Mechanics....

In these 7-8 years i wasnt active in MTBR i have some stories to tell.....

You wouldnt get a 6.25wt fluid, thats sort of what I was trying to get at. You'd get a mix of two fluids with sort of unknown specs, somewhere between the two you mixed. They have different additives and different viscosity indexes.

It would work though. It wouldnt be 5wt, but that doesnt really matter either. If it would make you feel more confident in doing so, you certainly can mix them 50/50 and call it good. It is good enough... its just not 6.25wt.
:thumbsup::thumbsup:
 
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