Techinally, it's not made by Valvoline. It's made by Ashland, who also makes Valvoline, and some other private brand stuff.
And the reason it's "cheap" is because it's probably a bit down on the add-pack compared to a brand like Valvoline. But in no way does that make it bad stuff. It is made to meet specs just like any other product. It just may not "exceed" the specs to such a degree as some of it's competitors in the big brand names.
I see no reason not to use it. I've run both the Napa dino and synthetic fluids, when I can get them on sale. They work fine.
Napa brand is produced by Ashland/Valvoline. I use Napa HM oil and it gives exactly the same performance and wear as Valvoline Maxlife. It's usually $2.00 and change less per quart than name brand Valvoline. I run Napa HM 10W30 in my Dodge and Napa 5W20 conventional in my girlfriend's Honda. Both oils work fine in both vehicles. You can use the Napa brand with confidence.
I used valvoline all climate in my VW for the first 100K miles, and then switched to the Napa brand and ran that for the second 100K miles. I sold it running strong at around 225K miles and it never burned a drop or had anything done to the internal engine.
Having said that, it never went beyond 3000 miles on an oil change.