3.6HTHS with a KV100 of 12.4 gives a KV100/HTHS ratio of only 3.4. (I prefer to think of it this way to avoid having to think of a small decimal being bigger). For reference, I show the HPL 5w30 Euro to be 3.35 when similarly calculated. That's some VERY good company for this valvoline to be among.
My local Napa has the 5 gallon box of this stuff for $169 or ~$8.50/qt.
Given the certs, viscometrics and cost, perhaps this oil is a contender flying under the radar? For reference the 5w40 grade in the same line has an HTHS of 3.7, just one tenth higher.
I'd be be curious to see a VOA of this (none in that forum that I can find), the API SL suggest perhaps full SAPS add pack?