Dear Tom and Ray:

My dear husband and I have entered into a heated debate about the quality of gas. My less-than-informed husband insists that gas from quick-stop-type gas stations is a lesser quality than that of the big oil companies. My supposition is that there are only a few oil-refinery companies in our country and that "all gas is created equal." We are in agreement that there is a difference among octane. Could you please let us know which is best to put in my car, and then I can put my dear husband back in his place! -- Anne

RAY: It's not that simple, Anne. All gasoline sold in the United States meets Environmental Protection Agency requirements. So the short answer is, you can put anything into your car from Chevron down to Panther Squat, and it'll run fine.

TOM: The only difference between gasolines is in the contents of the "additives package" they use. The stuff you buy at Fred's Gas & Herring comes from the same holding tank as the stuff at Chevron, Shell or Texaco. But some brands use an additives package that does a better job of keeping your valves and your electronic throttle clean.

RAY: Back in 2004, several big carmakers -- GM, Honda, Toyota and others -- were unhappy with the detergent performance of gasoline, because they were finding deposits inside their beautiful engines. So they got together and created some new gasoline standards that are tougher than the federal standards. They called the gasoline that meets these higher standards "Top Tier" gas.

TOM: The companies that voluntarily agreed to sell only Top Tier gas in the United States are: QuikTrip, Chevron, Conoco, Phillips, 76, Shell, Entec, MFA Oil, Kwik Trip/Kwik Star, Somerset, Aloha Petroleum and Texaco.

RAY: So you won't find Joe's Gas and Step Stool Emporium on that list, but you will find a mix of major brands and smaller "no-brand" gasoline distributors. You'll also notice the absence of some VERY major brands, like the guys who drove the Valdez. Not to mention Mobil, BP, Gulf, Amoco, Sunoco, Hess and others.

TOM: Does it matter? It depends. Honda, BMW, Audi, VW, Toyota and GM think it does. But if you use the gas with fewer detergents and end up with carbon buildup after 100,000 miles, you can often get rid of it with a few cans of engine cleaner. You might even be able to get rid of it by using Top Tier fuel for 10,000 or 20,000 miles. So it's rarely an irreversible problem.

RAY: But if you drive a high-end car, or you want to be sure you never get any buildup on your fuel injectors or valves, you have to use Top Tier gasoline at least most of the time.

TOM: One other thing to keep in mind; the list of Top Tier providers might change. To see the latest list of Top Tier gasolines, go to their Web site, www.toptiergas.com.

RAY: And as for your husband, I'm not sure why you want to put him in his place, Anne. My wife is always trying to get me OUT of my place -- which is in front of the TV. Asleep.