The number of Mountain West motorists buying higher-priced premium gasoline has nearly tripled in recent years - but many are wasting money because their cars don't need the higher octane fuel, a government study said.

Only 5 percent of all gasoline sold in the region in 1984 was premium grade, but that increased to 13 percent by 1989. Nationally, the percentage of all gasoline sold that was premium increased from 14 percent to 23 percent."At the same time, however, the number of new cars needing premium gasoline, based on auto manufacturers' recommendations, has declined," said the study by the U.S. General Accounting Office, the research arm of Congress.

The report was compiled at the request of Sen. Howard Metzenbaum, D-Ohio, chairman of the Senate Judiciary Subcommittee on Antitrust, Monopolies and Business Rights, who wanted to see if "consumers may be needlessly buying higher-priced premium . . . when regular unleaded gasoline would meet their needs."

The GAO confirmed the senator's suspicions that consumers are wasting a lot of money.

"Consumers could be spending from $491 million to about $4.3 billion annually for premium gasoline that the studies show is not required," the study said.

Local refiners and auto mechanics in Utah would agree because Utah's higher altitude renders the anti-knocking additives in premium gasoline useless in most new cars.

Unleaded "plus" and premium grades are more expensive because it costs more to refine them to achieve a higher octane rating. The octane rating posted on a service station fuel pump measures the properties in the gasoline that prevent engine "knock" or "ping," occurring when the compressed fuel-air mixture burns unevenly.

Most auto manufacturers warn against using fuels with an octane rating lower than 87 to avoid loss of power and even serious engine damage. But most regular unleaded fuel in Utah sells at an octane rating of 85.

"It's not really harmful (in Utah) because at a higher altitude you don't need that high of an octane," said Dave Love, service manager at Rick Warner Ford. With much of Utah at 4,000 feet above sea level and higher there is less oxygen in the air, Love explained, making the air-fuel mixture in the engine as rich as a higher octane fuel at sea level.

Federal standards allow gasoline refined and sold in Utah to have an octane level 4.5 points lower than fuel sold on the coast. But local gasoline is usually no more than two points lower because Utah refineries also supply lower elevation markets.

The GAO listed several reasons why consumers may be buying the more expensive gasoline that many of them do not need.

"Federal Trade Commission officials told us that advertising may encourage the use of premium gasoline," the GAO said, noting the FTC finds most gasoline advertising promotes the benefits of premium.

Also, the GAO said the cost of premium in recent years has approached the cost of cheaper regular gasoline, apparently attracting more consumers who "perceived it as a better product for their vehicle."

Many luxury and high-performance vehicles require premium grade fuel, as indicated in the owner's manual. Some conditions, such as the car getting older, also may increase the need for premium.

The GAO said, "In general, as a car ages, its octane requirement increases by about 5 octane points. Most of the increase occurs within the first 15,000 miles. The increase is due primarily to a buildup of carbon deposits in the combustion chamber."

Love said that increase is also more critical in luxury and high performance vehicles than standard cars. Changing oil can reduce carbon buildup, he said, and newer computer equipped cars can automatically adjust the engine's timing for buildup and different octane levels.


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Thin air means rich fuel

With much of Utah at 4,000 feet above sea level and higher there is less oxygen in the air, making the air-fuel mixture in the engine as rich as a higher octane fuel at sea level.