Be careful that you don't poison your car with ethanol, the alcohol fuel made mostly from corn.
Phil Sielatycki came close to an accidental overdose at a Shell station in Apex.
He parked his Audi, swiped his credit card and lifted a yellow fuel nozzle on a blue pump marked "E85 - 85% Ethanol."
He chatted with his 9-year-old son, Ted, who climbed out of the car to unscrew the gas cap. They didn't notice a few stickers on the pump including a yellow one that read:
"Stop! Not Gasoline! E85 is designed to operate in Flex-Fuel Vehicles (FFVs) only."
Luckily for Sielatycki, the Road Worrier lurked nearby.
Ethanol is familiar around gas stations and in our tanks. Much of the gas we buy is 10percent ethanol - and that's no problem.
Federal rules and car warranties agree that so-called E10 won't hurt our cars. Gas stations no longer have to notify us when we're pumping only 90 percent gas.
Meanwhile, a save-the-planet campaign of marketing and public subsidies is pushing Americans to buy more ethanol.
It is promoted as a renewable fuel to help clean the air and curb our thirst for imported fossil fuels. There are debates about the wisdom of converting food crops to car fuel, but the ethanol lobby seems to be winning. Prodded by green groups and agri business interests, Congress has mandated a big increase in ethanol use.
But ethanol has drawbacks.
It packs less power than gas, with poorer fuel economy. The difference is slim with E10 fuel, but E85 - only 15 percent gas - delivers roughly 25 percent fewer miles per gallon than 100 percent gas.
And compared to gas, ethanol is more corrosive to metal and rubber engine parts. A flex-fuel car has fuel and emissions systems modified to resist the damage, so it runs well on either gas or E85.
There's a new push to boost ethanol levels in regular gas from 10 percent to 15 percent. Manufacturers caution that more ethanol might damage non-flex cars - and lawnmower, boat and other gas engines.
Sielatycki, 44, blanched when the Road Worrier warned him that his non-flex Audi wasn't made for 85percent ethanol.
"I wasn't paying attention," he said as he canceled his purchase. "But the thing is, you don't usually pay attention when you come and fill up."
Only 7 million of the 250million U.S. vehicles are flex-fuel. Fewer than 2,000 pumps nationwide dispense E85 now, including three in the Triangle and 10 more across the state. These numbers are expected to rise.
"Ethanol is here to stay," said Craig Stephenson, vice president of Cary Oil Co., which took advantage of government grants to install an E85 pump at his Apex Shell station.
Price subsidies keep E85 cheaper than gas, by 10cents to 35 cents a gallon. That makes it attractive to some drivers who should steer clear.
"Sometimes you've got customers who are not accustomed to looking at the fuel type," said Mack McLamb of Dunn, president of Carlie C's IGA, which sells E85 at a Benson station. "They're looking at the price. They see which one's the cheapest, and they push that button."
McLamb recalls two customers who had to have their cars towed and their tanks drained after they made the E85 mistake. One driver barely made it home before the car stalled. The other car broke down next to the fuel pump.
For Kerry Wilt of Cary, the damage was serious and the cause, at first, was a mystery.
His wife's Accord stalled the day after she unknowingly tanked up on E85. After three trips to the Honda dealer and $700 to replace ruined fuel injectors, the mechanics were still puzzled.
"They said, 'you've got bad gas,' " said Wilt, 47. He discovered it was E85 when he dug out the receipt.
"There are probably a number of people who've had this problem and don't realize what happened," Wilt said. "It's like food poisoning. You don't always know where you got it."
The Environmental Protection Agency is considering more urgent warnings for those E85 pump stickers.
Proposed new language for E85 would say that "the use in non-flex fuel vehicles is prohibited and may cause damage to the vehicle."
A skull and crossbones might help, too.