For long long term storage as you are describing, you may want to remove the fuel from the boat tank.
If you can obtain alcohol free fuel, often called REC 90, mix oil to about 50:1 in a separate container and add the correct storage amount of 2+4 Fuel Conditioner and take the boat out and run it if possible so the new mix with circulate throughout the motor, then run the winterizing procedure. Grease the fittings and steering, change gear oil wash and wax the motor. Service wheel bearings on the trailer. Fill up the oil tank.
If you cannot take the boat out for a run, then operate the engine on a flusher several times of at least 15 minutes each. It takes a long time at idle to use up the amount of old fuel inside the VST.
"There is never just one thing wrong with a boat";
-- Travis McGee, main character in a book series by John D. McDonald
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.
The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.