The only thing that you should concern yourself with is the octain. Brand does not matter. All gas is essentally the same except for the additives that the different brands add. I saw a show on refining oil and they mentioned a cross US pipeline that the Oil companies use to move gas across the country. The company puts gas in at one end and then takes some out of the other end. So Mobile gas put in at one end may be Shell gas that Mobile takes out at the other end. The govt have restrictions on the Octain of gas so in the end it is all the same.