TorQ ****** is correct. In fact, for the vast majority of gasoline sold in the US, the base fuel is "fungible" or exchanged. For example, US refineries fill pipelines with 93 octane, pipelines fill storage tanks, and only when a tank truck is filled is the gasoline additized. It is the additive that makes one fuel different than another.
Minor exceptions: Amoco markets their gasolines in some areas as "clear" because their refineries use some different processes. But because it costs money to keep this product segregated in the pipeline and storage systems, it's not available everywhere. Same for non-standard octane grades, such as 94 or 95.
Vehicle tests show that additives in gasolines should have completed their "cleaning" job after 5 tank fulls. If you think you have a deposit problem and it's not going away after 5 tanks, time to switch. Same tests show that convenience store brands almost always only have a "maintenance" level of additives, while *some* majors have a "clean-up" level of additives.
