Gas station question please help?

It could be the cold weather because the computer sets your car to run rich until it's warmed up using more gas. Ethanol is added to gas by state law in the most of the midwest. If you're in a state that requires it there are no stations selling "straight" gas. There is no difference in gas between brands or stations. All of the gas in the upper USA comes there through a series of pipelines from Texas and the Gulf. The pipelines are shared by all of the oil companies. They put gas in at the refinery and take it out at a distribution terminal but everybodies gas gets mixed together in the pipe. There's no way to know where the gas you're putting in your tank came from.