You'll know you're filling up with the good stuff if you spot a small green sticker on the pump that says “TOP TIER Detergent Gasoline.” As of early 2022, the following stations sold Top Tier gasoline in the U.S.: 76, ARCO, Aloha, Beacon, Breakaway, CITGO, Cenex, Chevron, Conoco, Costco Wholesale, CountryMark, ...