The fight against a higher blend of ethanol in gasoline has heated up with two automotive trade groups, small-engine makers and marine manufacturers expected to take court action on Monday.

At stake is an Environmental Protection Agency ruling that boosts the amount of ethanol allowed in gasoline for newer vehicles, a victory for ethanol producers but upsetting for engine makers who say the corn-based fuel additive will damage some vehicles and outdoor power equipment.

Most gasoline now contains up to 10% ethanol, which engine makers say is safe to run in their products.

Yet boat engines, lawn mowers, snowmobiles, generators, chain saws and other small-engine equipment could be permanently damaged from using a 15% ethanol blend allowed under the recent EPA ruling, according to the Outdoor Power Equipment Institute.

The small-engine makers have joined the Alliance of Automobile Manufacturers and the Association of International Automobile Manufacturers in objecting to a higher ethanol blend. The National Marine Manufacturers Association, which includes Fond du Lac-based Mercury Marine Inc. as a member, also has joined the fight.

On Monday, the groups are planning to file a petition in the U.S. Court of Appeals, in Washington, D.C., to block the implementation of the higher ethanol blend - which is expected to be available in 2011.

"It's risky business pushing this fuel into the market," said Kris Kiser, executive vice president of the Outdoor Power Equipment Institute, which includes Briggs & Stratton Corp. and Kohler Co. as members.

"It will destroy your boat engine, your chainsaw or your lawn mower, but the label on the fuel pump won't say that," Kiser said.

Ethanol advocates say the EPA ruling was a victory for grain-producing states and the biofuels industry and should not be reversed.

"We feel that ethanol is safe for engines," said Joshua Morby, spokesman for the Wisconsin Ethanol Coalition.

The EPA stopped short of approving the use of 15% ethanol in older automobiles and small engines. But the agency said it could expand the approval to older cars and trucks once further tests are completed.

That's alarming to small-engine makers who worry that higher ethanol blends will cause confusion in the marketplace and could supplant lower ethanol blends available to consumers.

"The problem is that people will choose whatever fuel is cheapest, and that's likely to be the 15% ethanol," Kiser said. "And the fuel they put in the tank of their car will be the same fuel they put in their gasoline can" for use in small engines.

In the petition that's being filed on Monday, the small-engine makers and automobile manufacturers say they have about 400 million engines in the U.S. and that allowing the use of 15% ethanol could be disastrous.

They want the EPA decision remanded back to the agency and are requesting judicial review over whether the agency's "partial waiver" approval for 15% ethanol was a violation of the federal Clean Air Act , which limits the circumstances under which new fuels are approved.

"None of us believe the EPA should approve a fuel for some engines, and then just let the marketplace sort it out," Kiser said. "It makes consumers guinea pigs. There's going to be a lot of misfueling."

Almost without exception, current off-road engines are not designed to run on 15% ethanol, according to the manufacturers.

Ethanol advocates disagree, saying that testing has proved the fuel won't harm engines.

"It's not in our interest to introduce a fuel into the marketplace that would damage engines," Morby said. "And we are confident that people are smart enough to put the right fuel in their fuel tank."

The court action follows objections by other groups opposed to ethanol and its tax subsidies.

"Shoveling out billions of dollars for oil companies to blend dirty corn ethanol into gasoline, if even for just another year, is a waste of taxpayer dollars," said Kate McMahon, biofuels campaign coordinator for Friends of the Earth, an environmental group.

Ethanol isn't a dirty fuel, Morby said.

"And I would be glad to have a discussion comparing the tax subsidies for the oil industry with ethanol," he added.