1991 Johnson/Evinrude EI Outboards 2.3 thru 8 Service Manual, Page 61Get this manual
Fuel Requirements
Minimum Octane Models Recommendation See fuel classifications below(R+M)2 "AKI" "RON"
PCE0020
Preferred Fuel: Any regular unleaded, regular leaded, or premium unleaded gasoline having the recommended octane rating and not extended with alcohol is the preferred fuelAcceptable Fuel: Any of the above gasolines with up to 10 alcohol by volume: 10 ETHANOL METHANOL with cosolvents