Fork Oil VI

[msparks]

quote:

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Originally posted by satterfi:
I've been investigating different fork oils to compare it to the type I've been using (Spectro 5w).

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Amsoil has some cross references on their site to other popular brands, maybe this will help you:

AMSOIL STL #5 cross references to the following lubricants:
Spectro SPL Ultra Light Ohlins Front Fork #5
Race Tech Light Klotz 5W
Maxima Shock Fluid RydeFX
Silkolene Pro RSF Golden Spectro Very Light
Belray Fork 5W Bilstein Bilmst 3030
Redline Light SLP Light
PJ1 Fork Oil Showa SS05
Belray HVI 5W

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AMSOIL STM #10 cross references to the following lubricants:
Spectro SK400 Shock & Fork Oil Maxima Fork Oil 10
Ohlins Front Fork Fluid #15 Spectro Fork Oil 10W
Redline Medium Belray Fork 10W
Klotz 10W Race Tech Medium
Belray HVI 10W Harley Davisdson Fork Oil Type B
Harley Davidson Fork Oil Type E Spectro SPL Very Light
Fox Racing Oil


Here is a link that has it broken out in a table that is easier to read, hope this helps.
http://www.amsoil.com/products/stl.html

 

[satterfi]

I've been investigating different fork oils to compare it to the type I've been using (Spectro 5w).

I thought I found the ultimate with Spectro SX which has a viscosity index of 400.

That was until I read the fine print. "For optimum performance, change every race."

 

[Jay]

That's a phenomenal VI! I've never seen any fluid that stable. It must oxidize easily? Maybe that's why the frequent changes.

 

[Hirev]

That is unreal.

Sounds like you need a full time wrench to use that stuff. I don't use many things Honda put out oil wise. But I have had good luck with Honda SS-7 5w suspension fluid. The W/P forks on my KTM needed help. And this stuff Did seem to help me out. I just change it once a year so far no rust.

 

[userfriendly]

You will have to learn the ISO viscosity grades and apply them to suspension fluids. That way you can compare the various brands and their weights to each other.
Yes there are fluids with 300+ viscosity indexes. That means those fluids will not thicken much when chilled and is the total opposite of what a suspension other than a jet aircraft or snowmobile needs.
In my opinion and from test results, I found that the higher the flashpoint, the better the suspension fluid acted at operating temperature, and the fluid lasted longer as well.
In a cold application like a snowmobile's suspension, go for the high VI values.
Ask me why and I will tell you the rest of the story.

 

[satterfi]

Here's a good list of suspension fluids.

Dirt tech

I'm giving Bel-Ray 5 wt a try. It's a little too thin as my rebound damping adjusters are almost screwed all the way in.

Next time I'll try a 50/50 mix of Redline lightweight and medium to shoot for a viscosity of around 25cst at 40C.

 

[userfriendly]

An ISO 22 AW hyd fluid would be very close, or a 22/32 blend. Much over 27ish seems to slow down the suspension's quick rection to small bumps and washboard.
If you are finding your MX bike likes suspension fluids in the 32-46 range with the adjusters closed up, consider a valving change. Make sure your spring rates and sag are right for the bike and rider combo first.

 

[satterfi]

Race-Tech did my front end. Lindemann Engineering did the back end.

I just don't know what I'm doing and need the help of experts when it comes to set up. It's been money well spent.

BTW, this is a road bike, not a dirt bike.