How to Convert to E85 Ethanol

Updated April 17, 2017

The process to convert your gasoline-only powered vehicle to E85 ethanol is similar to the process of converting your vehicle to an ethanol-only vehicle. E85 ethanol is a flex-fuel, which means that your vehicle will be able to operate with gasoline or a hybrid mixture of 85 per cent ethanol and gasoline. You need to convert a gasoline- powered vehicle to accept E85 ethanol or your "check engine" light will turn on because ethanol contains less energy than gasoline.

Change your vehicle's oil and oil filter before you begin. You can choose to get this done by your mechanic if you prefer. You may also want to get your mechanic to make sure that your vehicle is in proper working condition before you begin the process. This process can cost you several hundred dollars, so it probably is not worth doing on a car that won't last you very long.

Purchase an E85 adaptor kit that fits the make and model of your vehicle. Several different brands are available on the market, some will contain everything you need, and some may require you to purchase extra components. Make sure you read fully what is included in each kit before you purchase, and if extra items are needed, make sure you purchase them before you begin the process.

Add engine-protection chemicals to your engine's oil after you have changed the oil. You do not want to add it to old engine oil, so make sure to add it after you have put in the new oil. Add upper-cylinder treatment to a full tank of gasoline in your vehicle. The engine protection chemicals and upper-cylinder treatment typically are included in the E85 adaptor kit.

Mount the computer flex-fuel adaptor to your engine. You must find the proper location to mount the adaptor on a solid surface. Each female connector lead must be able to be connected to the corresponding fuel injector, according to the Flextek website. Ensure that the unit and all wires are kept a safe distance away from heat sources. To secure the adaptor, drill two holes into the surface you wish to mount the adaptor on, not through the unit itself. Use the two self-tapping screws to secure the unit to the surface.

Clean your vehicle chassis, including removing any rust or paint until you have a clean metal surface. Attach the negative ground wire directly to the chassis where you cleaned. Bolt the ground lug to the metal chassis and secure the ground wire. Cover the area with paint or grease to prevent rust from forming.

Disconnect the original wiring harness. Connect the flex-fuel injector leads to each fuel injector. Connect the female leads into corresponding fuel injectors and the male ends into the factory female plugs in the wiring harness.


Typical mounting choices are on the firewall or inner bumper wall.


You must drive through two full tanks of gasoline before using E85 ethanol.

Things You'll Need

  • Flex-fuel adaptor kit
  • Engine oil
  • Oil filter
  • Engine protection chemicals
  • Upper-cylinder treatment
  • Hand drill
  • 2 self-tapping screws
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About the Author

Nikki Van De Walle began writing in 2005. She has written articles for Humber College's "Daily Planet" and Guelph-Humber's "Radix." She graduated from the University of Guelph-Humber in 2010 with honors, receiving her Honors Bachelor of Applied Arts in media studies as well as her Diploma in Journalism.