NOACK & Shear

[WyrTwister]

Please excuse my entry level questions .

My limited understanding is NOACK is a measurement of how prone a fluid is to evaporation loss at high temperature ? I would think , everything else being equal , a " thicker " fluid would have smaller loss ?

I have always read that hydrocarbon lubricants are a mix of long chain molecules ? I am guessing " shear " is when these long chain molecules are cut , and become more molecules , with a shorter hydrocarbon chain ?

Again , every thing else being equal , are " thicker " lubricants more resistant to " shear " ?

Thanks ,

 

[MolaKule]

There seems to be two separate questions here:

There are two NOACK/Volativity threads that might answer your question:

NOACk 1
and

NOACK 2


Here is a presentation that also might answer your question on Shear of PCMO's:

Shear Trends in Automotive Oils

and dnewton3's comments here:

Shear in HDEO's

 

[NYSteve]

If you dig deeper into NOACK you will see there are competing standards/thinking on how to even measure it. Can't find the article but went into depth on how the NOACK test has been revised and how their is still discussion on what future NOACK testing looks like. Used to place a lot of emphasis in NOACK and now just ignore it fwiw

 

[CourierDriver]

Here you go everybody, knock yourself NOACK out, lol

https://www.mt.com/us/en/home/supportive_content/matchar_apps/MatChar_UC252.html

 

[CR94]

"Shear," not "sheer," which would mean it's so insubstantial that you can see through it!