This viscosity blending calculator link is great, but I am afraid someday it could become unavailable. Also you always have to log on to use it. Does anybody have the formulas for these calculations? I am really only interested in the 100cSt values. It would be nice to be able to plug it into my pocket calculator or run it on a spreadsheet. Thanks.

Couldn't wait. It is the correct equation. I ran 50/50 mix of cSt 10.5 with cSt 13.5. Both the online calculator and the equation gave me 11.9. I tried 5% 100 cSt with 95% 13 cSt and the online calculator gave me 14.4 whereas my pocket calculator gave me 14.396.

I wonder if maybe this is the equation:
Log Vs = (n log V1 + (100-n) log V2) / 100
where Vs = viscosity sought
n = percent by weight of the first component of the blend having a viscosity of V1
V2 = viscosity of the second component of the blend.
I found it in this article.
I will try to run some comparisons between the above equation and the viscosity blending online calculator tonight to see if I get similar results.
Please don't comment on the article in this thread. Rather go to where I posted it in the Interesting Articles Forum. Thanks.

i was searchig for the link to see the information about the misxtures but i couldn´t open the webpage, so i was wondering if you have other link to see that info or if you can correct the url to can open it.
thanks