Most don't realize that very few gasoline stations are actually owned or operated by the oil company who's name/brand is on the station...(and the products sold do not come exclusively from any one source.
Thus when folks say they are boycotting BP - the only individuals actually hurt are the small business owners that own and operate as cluster of BP branded service stations.
All gasoline (from all regional refiners) is sent by pipeline to large (common) regional storage facilities where it is stored in common by octane grade, and then transported out for delivery to a wide range of retail stations.
Thus any one tank of gas in your car will contain product made from the “blended” oil produced by many different domestic and/or foreign entities - and then refined by a host of different refineries.