1988 Johnson/Evinrude "CC" 40 thru 55 Models Service Manual, Page 45Get this manual
Fuel Requirements
Minimum Octane Models Recommendations Pump Posted 67 "RON" 69
45 Comm55 Comm35,40,48,50
See fuel classifications below See fuel classifications below
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 maximum alcohol volume: 10 ETHANOL (ethyl alcohol) (may be called gasohol) METHANOL (methyl alcohol)cosolvent alcohols Unacceptable Fuel: Do not use any regular unleaded, regular leaded, or premium unleaded gasoline having more than 10 ETHANOL or more than METHANOL even if it contains cosolvents or corrosion inhibitor and regardless of octane ratingNote Alcohol extended fuels may result in engine running quality problems, vapor lock, or "fuel starvation" problems, or moisture absorption (phase separation) problemsIf running quality problems are experienced, switch to gasoline without alcohol as described in Preferred FuelOMC products have been designed to operate using the Preferred Fuel or Acceptable Fuel; however, be aware of the following: aThe boat fuel system may be different regarding use of alcohol fuelsRefer to boat owner's manualbAlcohol attracts and holds moisture which may cause corrosion of metallic parts of the fuel systemcMetallic and nonmetallic parts of the entire fuel system should be inspected frequently and replaced if signs of excessive stiffness, deterioration, corrosion, or fuel leakage are foundInspect at least annually