1980 Johnson 4HP Service Manual, Page 14Get this manual
ENGINE FUEL AND LUBRICANT RECOMMENOEO GASOLINE: Use gasoline with the following minimum octane numbersPUMP POSTEO OCTANE NUMBER Research Octane Number Most Commonly Used in the Past 86
BELOW 32 Follow ABOVE 32 mixing instructionsAdditional mixing is quired thoroughly shaking tank
SAFETY WARHIHG