1992 Johnson Evinrude "EN" 40 thru 55 Service Manual, P/N 508143, Page 28Get this manual
Fuel Requirements Minimum Octane Models 40RS, 45,55 40, 48, 50 Recommendations See fuel classifications below See fuel classifications below (R+M)2 "AKI" 67 87 "RON" 69 90
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
r::=J The use of premium grade fuels is specifically encouragedMost national brand premium fuels
contain detergent and dispersant ingredients advertised to reduce intake valve and fuel injector depositsThese ingredients also remove and prevent carbon buildup on pistons and ringsThese ingredients can extend engine life while maintaining high level of performanceUnacceptable Fuel: Do not use any gasoline having more than 10 ETHANOL or more than METHANOL even if it contains cosolvents or corrosion inhibitor, regardless of octane rating