The store-brands vary slightly in the regions, but most are done by the two different warren companies (Warren PP and Warren-Coastal). Napa is ashland but it is not Synpower... it has a weaker addpack.
Really any of the major store brands are good oil, some are very good. Some's add-packs outdo some of the major brands offerings but some of the major brands have better products. You really have to "peel the labels off" and ignore the name on the bottle and base things on the addpack/base oil characteristics.
The way I see it, a lot of the store-brands Syns are the same price as decent major brand's dino syn/blend offering and I would go with the store brand syn for that pricepoint. I am weary at stretching any dino for 7,500 unless it is an all in one shot 7,500 roadtrip on the highway. Go with a Syn with that OCI.
Unless you are shopping at the bargain-bin-no-name bottle in a gas station, it is hard to find a bad oil in a major retail place.