Noack volatility is like a lot of things concerning base oil stock, not near a problem as was in the past due to the new GF-3 specs. To base an oil's performance on base stock's performance is not always the best thing. Kinda like taking an musical band with all 20 or so musicians. singlarly, each one may be the top of the line in playing on time, and with precision. But then put a single drummer in that can't keep a beat, maybe even tends to drown out the instruments, then see how as a whole the band works to gether.
Like the band, the noack is one aspect of how well the base stock is going to hold and to base as to how well the band is going to sound based on one instrument or how well an oil is going to hold up based on one aspect of the base oil is not a true picture.
There is several stages to look at when looking at oil.
1.. Base stock's ability to..
a. hold up to heat (noack)
b. pumpability at cold temps
c. maybe flashpoint
d. operational viscosity
e. pumping viscosity
f. shear stability
2.. detergent packages...
a. how they hold up to acid resisitance
(tbn and detergent levels)
3.. Wear protection...
a. what kind of barrier additive is used
b. what levels of barrier additives(amounts)
These are just some of the things to look at, now, put it all together. If they play off key because one is higher pitched than the other(to much of one additive,not enough of the other), or off beat from the other band members(not playing well with other additives due to clash), Then you have an ok sounding band or maybe even a really sorry sounding band that only 10 beers could make them sound better(use an after market oil additive).
So back to noack, this tests oil up to 500deg for 1 hr?, your oil will not see this kind of temp for that duration therfore it like a lot of other things is taken as if the better the number the better the oil. case in point, if your oil only see's 350 deg f., but can handle 450-475 deg with no problem, will it work as well as the one that handles 500 deg? why not, it is establish that until it reaches 450 deg that's when you start with problems as 500 in the other example. So what if it doesn't last as long, what it does establish is that the base oil can resist heat longer so that does make it look like a possible good canidate for extending drain intervals, provided that the tbn oxidation levels can hold up which rely on the additive package to help the base oil to withstand.
So in my opinion, don't loose sleep on it, but like many aspects to oil, it along with other parts play a small role but put to gether, like the music band, it all will sound like sweet wonderful music when they all play together (like a properly blended oil) and that my friend is how you look at oils and determine if they are what you want, but listening to the end results being played by the band(doing oil analysis on your engine with your choice of oil) is the key to determining oil quality. This is one reason I provided an area for oil analysis to be shared so that many could see real life #'s instead of just bench #'s.
And thats the rest of the story. Goooooood day.