Monday, Aug. 25, 2003 | 11:48 a.m.
Rising gas prices can drive motorists to take unconventional steps in search of savings, but those who skimp on octane risk getting burned, experts say.
Shelley Sanchez of St. George, Utah, usually fills her 1991 Mazda Miata with premium fuel, but on her way home from California Sunday evening, she decided to cheat a little bit. She filled her sporty vehicle with 87-octane regular unleaded gasoline, saving a few bucks at the Vegas Valley Travel Center on East Lake Mead Drive.
Sanchez said she realizes "it's only a few cents difference in the long run," but when gas prices skyrocket, "it's mental."
But for those who own certain high-end vehicles, choosing fuel grades according to the price of gasoline can result in physical damage to the engine.
"It's a terrible idea," said Larry Thomas, chairman of the Transportation and Industrial Technology Department at the Community College of Southern Nevada.
Thomas said putting regular unleaded gas in a car that requires mid- or premium-grade fuel can result in "knocking," in which the compressed fuel-air mixture ignites in the cylinder prior to the firing of the spark plug. Possible consequences include rapid engine wear, decreased performance or even engine damage.
But Sanchez is certainly not the only one who has been dipping into the cheap fuel more in recent weeks.
"The price (of gas) has gone up 30 cents in three weeks, and a lot of the gas stations around here ran out of regular unleaded," said David Ferguson, cashier at the Rebel gas station on Eastern Avenue in Green Valley. Ferguson said that his store didn't run out of gas, but he has noticed a significant spike in the number of customers opting for the cheaper grade.
With savings on regular unleaded sometimes exceeding 20 cents per gallon as compared to premium gas, the 87-octane can be tough to turn down, especially for drivers who don't fully understand the significance of the different fuel grades.
Most of the time, Thomas said, "They don't realize they could be damaging their vehicle."
But, as Sanchez's case illustrates, there is another side to the story: When gas prices are low, many drivers splurge on premium fuel for cars that would work just fine on regular unleaded.
"A lot of people think they're using better fuel by using the high octane, but all they're doing is throwing money out the tailpipe," said Scott Ramer, parts and service director at Findlay Toyota in Henderson. "It does absolutely nothing."
While buying fuel of a higher grade than necessary is unlikely to seriously harm a vehicle's engine, Thomas said it can slightly hinder performance.
"Cars now are designed around octane ratings, so when a manufacturer says you should use 87 octane ... you don't want to use a higher octane, because the computer sensors see a change in the way the fuel is burned and change the way (the engine) runs," Thomas said.
"Most cars on the road just require the standard-octane fuel," confirmed Roger Keely, service director for Courtesy Oldsmobile-Isuzu-Kia-Mazda on West Sahara Road.
For the most part, Keely said, "Vehicles that require premium fuel label it right at the fuel door." If not, owners' manuals almost always specify the recommended grade.
Tom Burba of Henderson didn't have to leaf through his booklet to find out that he shouldn't put regular-grade gasoline in his new Nissan 350Z sports car.
"The dealer said, 'If you do it, you're dead,"' Burba said. Burba has taken the advice to heart -- though he occasionally casts a wistful gaze at the 87-octane button at the gas station, he said he chooses the premium fuel every time he fills up.
Drivers don't have to know what octane means to know what grade of gasoline to use, but Michael Alder, an instructor in the same program as Thomas at CCSN, explains it as a rating of the gasoline's ability to compress without igniting.
"It's a chemical question of how quickly it burns -- it actually slows the burn down," Alder said. The reason high-performance engines require a higher octane rating is because they compress the fuel mixture more before igniting it.
Alder said a surefire way to tell if a car needs higher octane fuel is if the engine emits an audible "pinging" as it runs.
"If they are running the grade of gas required, and it's pinging, then you might want to have it checked out by a professional for excessive carbon deposits in combustion chambers," Alder said.
If the driver is not running the grade of gas required, the pinging can be thought of as the engine's cry for help.
John McDonald of Green Valley said that's a sound he doesn't want to risk hearing from his Mercedes.
"I just wouldn't try it, because the car is so sensitive," he said. "Just cry about the price, is all you can do."
Sun reporter Jean Reid Norman contributed to this story.
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