Had to look up top tiers, I see quite a few are considered.
AAA top tier study
Top Tier Retailers
76, Aloha Petroleum, Amoco, ARCO, Beacon, BP, Breakaway, Break Time, Cenex, Chevron, CITGO, Conoco, Costco, CountryMark, Diamond Shamrock, Entec, Esso, Express Mart, Exxon, Fast Fuel, HFN, Hele, Holiday, Kwik Star, Irving, Kirkland Signature, Kwik Star, Kwik Trip, Marathon, Metro Petro, MFA, Mobil, Ohana Fuels, Phillips 66, PUMA, QT, Quik Trip, Road Ranger, Shamrock, Shell, Sinclair, Sunoco, SuperAmerica, SuperFuels, Texaco, Valero, Value America, Wow, and Win Win.
But not my usual Walmart/ Sam s gas.
Quick trip is similarly priced and close by.
I don't normally use a gas additive, other than Marvel Mystery oil very ocassionally.