Mechanic in a Bottle and/or Ethanol Shield works in gasoline blends up to E-85. One thing to remember is all ethanol blends over E-10 are not approved by the EPA for uses in power equipment, boats motorcycles or ATV's. Blends over E-10 are only approved for automotive use. Take a look at the following news announcement from OPEI and concerns over consumers misfueling with E-15 fuel.
Also take a look at this article and video where B3C is helping educate about today's bio-fuels.