Published: May 03, 2012 11:23 PM EDT
Updated: May 04, 2012 12:00 AM EDT

FORT MYERS, Fla. - When you fill up do you look for the cheapest price? We uncover that paying more for your gas may actually save you money in the long run.

Turns out, not all gas is created equal. We're not talking about octane, we're talking about brand.

Local mechanic Pam Oakes explains the logic.

"You know how you feel lousy when you eat junk food? Your car feels lousy when you eat junk food gas," she said.

Pam tells WINK that most drivers fill up with cheap junk food gas instead of looking for something called "top tier" gas. Top tier has nothing to do with octane and it has everything to do with the detergent level in the gas.

Several car manufacturers felt gasoline marketers were lowering the level of detergent additives in gasoline causing major problems for their products. So BMW, General Motors, Honda, Toyota, Volkswagen and Audi came together to come up with a cleaner burning gas.

"They say this is the formula that we need to have in our cars to have healthy fuel for our cars to run at peak performance, the least amount of emissions, and especially for those of us at the gas pump right now, the highest mpg," Pam explained. "So a handful of them said we can do this and this is what you hear now is top tier fuel."

Here in Southwest Florida only a few gas stations sell top tier gas like Shell, Mobile, Texaco and Chevron.

Pam showed us a valve from an engine where the driver used poor quality gas.

"You can see the pieces of carbon that adhered to it. It should be shiny. Look at all that crud on there. It robs you of mpg and takes money out of your wallet," she said.

That's because when the parts of your engine have carbon build up, your car works less efficiently.

"Think of carbon buildup in your vehicle and your car is trying to run with all that carbon in there. It's like you trying to run a marathon with your hand over your mouth. It's not going to happen," Pam said. "It's going to be hard on you, it's going be hard on the car. When it is hard on the car you're depleting the car's lifespan. For a few pennies more, do the top tier."

Pam says usually your gas mileage will increase so much, it will save you an entire tank of gas

"Then every four to six tank-fulls, you're going to get that refund. It's more than worth it," she said.

Another secret Pam wants to let you in on, a quarter tank is the new empty. Pretty much every car has a computer in it now and when you go below quarter tank it kicks into a diagnostic mode ruining your fuel efficiency. Your fuel pump sits in the gasoline to keep cool, so if you consistently go to empty, you're putting a lot of stress on your fuel pump that could cost you thousands of dollars! So she says fill up at quarter of a tank.

For more information on top tier gas, click on this link.