Ethanol mess with your car’s engine? You may be on your own

The ethanol industry is getting a rare run for its money in Washington in recent weeks as a number of lawmakers try to repeal the many tax breaks the fuel additive has received for years.

This has traditional critics of the industry stepping up their game, including the Environmental Working Group. The nonpartisan nonprofit has issued reports critical of ethanol in the past, and is weighing in this week with one that looks at concerns about the impact of ethanol on engine maintenance.

The EPA recently approved an increase in the amount of ethanol that can be blended with gasoline from 10 percent to 15 percent. There’s been some  concern that more ethanol will create added performance and maintenance issues with gasoline engines, however, and that car makers won’t honor service warranties if problems are traced to E15 problems.

So EWG called the U.S. headquarters of 13 major automakers (posing as regular consumers) and asked where the car companies stood on E15 and engine warranties.

Here’s a summary of their results, based on conversations with company reps:

Four companies said warranties would be voided if E15 caused engine trouble:

  • Lexus suggested using premium unleaded fuel with an octane of 91 or higher. Since E15 is not listed as a recommended fuel in its owner’s manuals, the warranty would be voided if using E15 caused engine problems.
  • Subaru said a vehicle’s warranty could be voided if an engine problem were traced to using E15. Subaru’s representative noted that some people recommend against higher ethanol blends.
  • Toyota noted that their owner’s manuals explicitly state that the warranty is only valid for blends up to E10, except for its limited number of flex-fuel vehicles.
  • Volkswagen’s representative suggested calling a local dealer but said that warranties would be voided if an engine problem were traced to the fuel.

Other companies gave answers that were more vague:

  • BMW referred consumers to a local dealership.
  • Dodge’s representative had not personally heard of E15 before. Instead, EWG was referred to a local dealer and EPA’s website, which provides no information by car makes or models.
  • Jeep’s representative said using E15 in vehicles manufactured after 2007 should be fine, but that there are concerns with vehicles that fall in model years 2001 to 2006 . The company recommended checking with a dealership to see if the difference between E10 and E15 would matter for a particular vehicle, and also suggested referring to the owner’s manual.
  • Honda’s representative said only E10 is covered by the warranty in the owner’s manual and there is a good likelihood that it would be voided if a higher ethanol blend were used. It, too, recommended checking with a local dealer.

Some companies said they knew nothing about E15 and only had information about E85, or referred to the cars’ recommended octane level:

  • Ford’s owner’s manuals say its vehicles should not use fuel with more than 10 percent ethanol. A representative mentioned that a few weeks prior, a customer had engine trouble after using 20 percent ethanol (E20) and warned that gaskets and seals can wear faster with the higher blends.
  • Saturn’s representative was not familiar with E15 but mentioned that E85 can only be used in flex-fuel vehicles, and that its cars are made with yellow gas caps to signal compatibility with ethanol fuel.
  • Buick said it does not make vehicles that are compatible with E15 and only had information on E85 and its use in flex-fuel vehicles. In the end, 87 or higher octane fuel was recommended.
  • Nissan’s representative confirmed that E15 is not mentioned in the owner’s manual and instead recommended using a fuel with 91 or higher octane content.

One company said its warranty would not be voided with E15 so long as the correct octane level was used:

  • Chevrolet’s representative indicated that owners should use regular unleaded gasoline of 87 or higher octane to avoid heavy “knocking.” The vehicle warranty would not be voided as long as that condition was met.
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