1978 Johnson 55 HP Outboards Service Manual, Page 14Get this manual
If the proper tube or filler type can is not available,
II'.u NOTE
Avoid the use of the following, as they will contribute to deterioration of your engine and shorten spark plug life: AVOID USE OF: Automotive oils Premix fuel of unknown oil quality Premix fuel richer than 50:1 ratio Some additives in 50:1 lubricant are subject to evaporationAlways cover partially used cans to prevent deterioration of lubricantFUEL MIXING INSTRUCTIONS: Always use fresh gasoline
install drainfill plugSlowly fill gearcase through oil level hole allowing trapped air to escapeInstall oil level plugTighten both plugs securelyAir still trapped inside gearcase will escape after motor is operated or allowed to stand in vertical position for several hoursRecheck level after motor test and refill as requiredENGINE FUEL AND LUBRICANT