I may have missed it but what national pre-owned car chain are you referring to? Carmax? If that is the case I would be willing to bet a steak dinner that they are not using any certain spec'ed oil for any of their cars. Each store buys tons of oil in bulk for the lowest price and just uses 5w30 for everything and the cheapest filters they can source.
If you are worried about the certs and specs, take it to the dealer and mention that or any indy shop where they source it or allow you to bring it.
If you are worried about the certs and specs, take it to the dealer and mention that or any indy shop where they source it or allow you to bring it.