This is one of those things that very few drivers really understand. Gas is gas right? Is there any reason to pick one brand of gas over another? Most people decide where to fill up out of convenience and price. Some people, however, swear by a certain brand of gas and think they can tell the difference between it and cheaper, off-brand gas. Are they full of it?
Carcomplaints.com notes that, while the EPA does require a minimum amount of detergents in all gasoline sold in the US, some companies go above and beyond and add their own concoction of detergents and charge an average of three cents more per gallon. To see if these added detergents made a difference, AAA did their own testing of Top Tier and non-Top Tier brands. After just one oil change, the cars using non-top tier gas had 19 times more deposits than those using Top Tier gas. They even found that switching to a Top Tier gasoline could help reduce deposits left by previous non-Top Tier gasoline use.
Consumer Reports says that these brands currently sell Top Tier gas in all grades:
"76, Aloha Petroleum, Amoco, ARCO, Beacon, BP, Break Time, Cenex, Chevron, CITGO, Conoco, Co-op, Costco, CountryMark, Diamond Shamrock, Entec, Esso, Express, Exxon, Holiday, Kwik Star Stores, Kwik Trip, Mahalo, MFA, Mobil, Ohana Fuels, Petro-Canada, Phillips 66, PUMA, QT, Quik Trip, Road Ranger, Shamrock, Shell / Shell V-Power, Sinclair Standard, SuperAmerica, SuperFuels, Tempo, Texaco, Tri-Par, and Valero."
Due to the small cost difference and proven efficiency losses deposits can cause, there is really no reason not to buy gas from a station that sells Top Tier fuel.