Grant you my data point count is low (10) across 5 vehicles (2 auto, 2 manual, 1 transfer case) that use ATF+4 in their transmissions. Blackstone Labs analysis of fluids taken at factory recommended service drain intervals have come back with no issues or concerns to be noted. Of those 10 tests, 4 were admittedly known or highly suspected factory fills (1 auto, 2 manual, 1 transfer case) which (not?) ironically exhibited the highest levels of "wear" indicators; expected as break in was occurring with them present. The rest (4 auto, 2 transfer case) were known Walmart ATF+4 refills. I'm not sure what else a consumer can do to actively verify their choice of fluid(s) is an intelligent one. As was noted, since ATF+4 is licensed, it appears to be more strictly controlled in terms of quality than most of the automotive fluids. Further, it's been well documented that Walmart's supplier(s) are generally top tier producers in their own rights, frequently with their Name Brand bottles sitting on the shelf next to the house brand. I also have numerous data points for oil changes analysed by Blackstone Labs, nearly all of which are from Walmart branded oil changes, and none of them have ever come back with a warning or concern from them.
Now filters, since they're harder to test reliably, I stick with NAPA/WIX that i buy by the case.
