The federal Environmental Protection Agency is considering requiring use of a blend of ethanol and gasoline known as “E15.” This is a risky measure that threatens to damage our car engines and saddle car companies with soaring warranty costs.

Corn-based ethanol, the type currently used in the United States, is a terrible transportation fuel whose production has serious environmental consequences and raises food prices for the world’s poor while delivering few net environmental benefits. Requiring higher blends of it to be put into engines not designed to handle those levels of the corrosive, water-attracting fuel without adequate testing is a gamble on a grand scale.

E15 is not a blend of 15 percent ethanol and 85 percent gasoline. Rather, according to Underwriters Laboratories, it is a blend of roughly 15 percent ethanol, with everything from 12-17 percent ethanol or more, depending on storage conditions. That percentage of ethanol matters because cars in existence today—except for the few certified as “flex-fuel”—were not designed to handle blends above 15 percent.

Upgrading a car to handle higher levels of ethanol generally requires modifying a wide range of components, including fuel tanks, fuel tank electrical wiring, fuel pumps, fuel filters, fuel lines, fuel level sensors, fuel injectors, seals, fuel pressure regulators and inlet valves.

It is not just our cars that are not designed for higher levels of ethanol, of course. Neither are existing filling station pumps and tanks—not to mention recreational boat engines, lawnmowers, leaf blowers, four-wheelers, snowmobiles, or anything else with a gasoline engine. Increasing the amount of ethanol required to be blended into our fuel supply is rolling the dice for every existing gasoline engine.

The problem is that not only can ethanol corrode metal, rubber and plastic surfaces with which the fuel comes into contact, but that ethanol also attracts water as it passes through the refining and fuel distribution network—an additional source of potential damage. Moreover, some contaminants that settle out in storage tanks over time are soluble in ethanol and can be carried into engines.

There is much we don’t know about higher ethanol-blends’ impact. For example, a German study by scientists at auto parts maker Robert Bosch found that gasoline-ethanol blends bought from gas stations had much greater corrosive effects than predicted.

Meanwhile, anecdotal evidence is piling up that higher ethanol blends in existing vehicles are problematic. In a May 2009 column, award-winning journalist Business Week Ed Wallace described cars with $1,000 or more damage to fuel pumps and Lexus’ 2009 recall of some 2006-2008 models because of pinpoint leaks in the fuel system caused by ethanol blends.

Just who will pay for the damage E15 could cause is unsettled as well, although we can be sure it won’t be Congress or the EPA. It would be unfair to ask consumers to pay the cost of ethanol-related repairs, but car manufacturers reeling under recession-related losses are no better equipped to bear the costs of a federal regulatory mistake.

There is no need for EPA to rush into what the Union of Concerned Scientists termed “a premature, unnecessarily piecemeal approach.” The pressure to do so comes from the politically powerful ethanol lobby and farm state senators, who successfully inserted an ever-increasing ethanol mandate into 2007 energy legislation.

Instead of conducting an unprecedented experiment on billions of dollars of Americans’ cars, lawn mowers, boats, snowmobiles, small engine tools and transportation fuel infrastructure, this politically determined mandate should be put on hold until proper testing can be done. does not condone or review every comment. Read more in our Commenter Policy Agreement

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