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Don't Be Swayed By Cheap Premium Gas

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With gas prices at a five-year low and regular unleaded gasoline selling for less than $2 a gallon in some areas, it might be tempting to treat your car’s engine to a tankful of premium gas — even though it’s designed to run on regular — to get the benefits of higher octane and additional additives.

Related: What’s the Most Affordable Car in 2014?

Save your money and don’t do it, said Mike Calkins, technical services manager of AAA, a travel services organization.

“Use what the manufacturer says to use because there’s not enough benefit, if any, to moving up to a higher grade of gasoline. You’re just spending money unnecessarily,” Calkins said.

Burning premium gas in a car that only needs regular will not increase gas mileage, boost acceleration, reduce emissions or do more to remove those troublesome “engine deposits” that the oil companies warn about in their commercials.

The main difference between premium and regular is that premium has a higher octane rating, 91 or higher instead of 87.

“The octane rating is a measure of the fuel’s ability to resist knock in the engine,” Calkins said. Knock, or “pinging,” occurs when fuel detonates in combustion chambers before being ignited by spark plugs. Using a lower-octane fuel than is required can cause knock.

“If the engine in your car was designed for regular fuel and does not knock on regular fuel, there is no advantage to putting premium fuel in it because the additional antiknock capabilities don’t serve any purpose,” he said.

The national average price for regular gas was $2.48 a gallon on Thursday, the AAA Daily Fuel Gauge Report said, and the average for a gallon of premium was $2.89. Gas prices have fallen for 84 consecutive days, and the national average for regular is 74 cents cheaper than a year ago.

Regular is widely available for less than $2 a gallon in states such as Texas, Oklahoma and Missouri, which had the lowest statewide average at $2.15. In the St. Louis area, premium was going for as little as $2.23 a gallon, according to

Instead of spending more to put premium gas in an engine that doesn’t need it, Calkins said a better investment would be to buy Top Tier gas instead. Top Tier is a voluntary standard adopted by several major oil companies to use more engine-cleaning detergents than is required by the EPA.

Arco, BP, Chevron, ExxonMobil, Phillips 66 and Shell are among the brands that have adopted Top Tier standards. Several vehicle manufacturers, including BMW, General Motors, Honda, Mercedes-Benz, Toyota and Volkswagen, recommend using Top Tier gas. Calkins said Top Tier gas usually has at least two times more detergents than required by the EPA, and vehicle manufacturers say using it results in less fuel-injector fouling and engine deposits.

“I would encourage people to use Top Tier gas, but with the recognition that it’s typically at name-brand stations, so you’re going to probably be paying more than you would for no-name gasoline,” he said.

With gas prices sliding for 12 straight weeks, regular was averaging more than $3 a gallon in only two states, Alaska ($3.31) and Hawaii ($3.65). The average was below $2.50 in 26 states.

Price declines accelerated in late November after OPEC decided not to cut production to try to stem falling oil prices. Since then, oil prices have continued to tumble, dragging pump prices down as well.

The national average for regular has fallen 39 cents the past four weeks, AAA said, and several states have seen bigger declines. The average price has fallen 57 cents in the past month in Indiana and 62 cents in Idaho and Michigan. photo by Aaron Bragman

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