1991 Johnson/Evinrude Models "EI" 40 thru 55 Service Manual, Page 26Get this manual
FuelOil Ratios Lubricant
Only the following lubricants should be used:
Evinrude Outboard Lubricant Evinrude XP Outboard Lubricant Johnson Outboard Lubricant Johnson GT Outboard Lubricant OMC 2-Cycle Motor Oil
They are formulated to give best engine performance with least combustion chamber deposits, least piston varnish, maximum spark plug life, maximum corrosion protection and best lubricationIf Evinrude or Johnson Outboard Lubricant or OMC 2-Cycle Motor Oil is not available, another NMMA certified TC-W II oil may be usedLook for the certification information on the container labelRunning or storing an engine on leaner than recommended fuelloil mixture may result in powerhead damage
Avoid the use of the following as they could damage your engine andor shorten spark plug life: Automotive oils Premix fuel of unknown oil quantity Premix fuel richer than the recommended ratio Oil and gasoline leaner than the recommended ratio