Fuel Wars

(CBS)  Gasoline has been rising, on average, four cents a week this summer driving season, and is now at a record high. So some drivers are bypassing big-name stations and buying discount gas.

But does the cheaper fuel harm your engine? CBS News Correspondent Sandra Hughes has the story.

It's a filling-station face-off: name brand versus discount gas.

"I have to get the best price I can get, right?" said one consumer.

Right! But is discount gas really the same as brand-name gas – even though it sometimes costs up to 20 cents a gallon less?

"It's 20 cents cheaper? Score!" said another gas-pumper.

But is it good for your car?

Many who opt for the cheaper gas haven't considered this question, but a lot of people who buy brand names have.

"I don't know whether it's fact or fiction, but I always feel comfortable with the bigger name," said one brand-name consumer.

The reality? The answer is both "yes" and "no."

"Gasoline comes from just a few terminals, yes" said California Energy Commissioner Jim Boyd.

Different distributors do fill up their tanker trucks at the same terminal. But brand names argue they have a higher quality because they put more additives that help the car's engine run clean.

But discounters like Costco say it doesn't matter.

Hughes asked Scott Kirby, an assistant manager at Costco, if customers ask whether discount gas is good for their cars.

"Yeah, every now and then a member will ask, and we just reassure them that the gas comes from a reputable source, and it is good quality gas," Kirby said.

That wasn't the case back in 1979, during the energy crisis when people ruined their engines buying unregulated discount gas. Now, even discount gasoline must meet minimum EPA standards.

"Cheap gas will more likely foul up the spark plugs... not immediately, but in due time." said Otto Lopez, an independent mechanic.

None of the name brand gas companies we contacted would talk to CBS News about why their gas is better.

But some automakers – like BMW, General Motors, Honda and Toyota – have recommended a list of stations that provide what they call "top-tier" gasoline, which includes QuikTrip, Chevron, Conoco, Phillips 66, 76 , Shell and MFA Oil Company.

So who wins the face-off?

"The best advice we can give at the moment is look for the best price," Boyd said.

If you do buy discount gas, the experts recommend buying a detergent additive and pouring it into your tank every few thousand miles. They also suggest hitting the brand names for a fill up occasionally for the cleaning additives.

It's a lesson Edward Matthews who drives a vintage Mercedes learned a long time ago.

"I'm saving 40 cents a gallon," he said.

Forty cents a gallon, he said, adds up "more than you can think."

And it's kept his prized possession purring for 40 years.