Valero ( VLO ) and Marathon Oil ( MRO ) are just two firms that have resorted to moving product abroad in order to avoid the impossible situation. While it is true that gasoline prices are typically higher during the warmer months as demand also rises, the current spike is also due to some behind the scenes issues that many consumers may not be aware of. The law also states that the amount of ethanol used will steadily increase as time goes on, forcing refiners to rely more and more on this alternative fuel source.