Well, Ashland/Valvoline will not admit it in plain English, whether Napa brand and Valvoline are the same oil. It has been discussed here a few times. I emailed Valvoline and got a cryptic response. As far as I know, Napa and Valvoline are the same. Some have said there are different add packs in each oil. Whatever differences there are, are very minor and insignificant. It doesn't make good business sense to me to have 2 different add packs to add to the same oil just in 2 different batches. Both Napa and Ashland/Valvoline make more money when they sell Valvoline branded oil so I guess they have good reason not to tell whether both are the same. I do know there was a UOA done on Napa Synthetic and it was nearly identical to Synpower, except for a couple of components. I don't know all the technical aspects of the ingredients or add packs in oil. I have never had a UOA or VOA done.
What I do know is I have been using Napa brand 10W30 in my truck and Napa 5W20 my gf's car now for a litle over a year and have had absolutely no problems at all with either one. I changed from Valvoline to Napa brand last year when oil and gas prices started going sky high. I realized I could save money on Napa oil and get the same results as name brand Valvoline. Valvoline and Napa pour the same from the bottle, they have the same color and even have the same smell. I get exactly the same MPG and performance from Napa as I did when I used Valvoline. It even takes on the same greenish-yellow color on the dipstick around 500 miles as Valvoline did, and after that it turns a brown color that darkens over the length of the OCI, same as Valvoline did.
I have been waiting a very long time for this sale. This is the first time I have seen Napa brand on sale since I began using it. I don't know how often they run a sale on it. Probably not again for a pretty good while so I want to stock up on both oil and filters this month. Napa has ProSelect oil filters on sale for August too.