[8D]
Easiest possible way, and well tested is to use a metal coffee can 2/3 full of antifreeze warmed up on your BBQ. The engine does not need to be disassembled. The antifreeze is formulated to not harm metals, brass, rubber, gaskets, etc. Wife does not need to worry about her cookers, etc.

Heat the antifreeze to a temp short of boiling and soak the engine for 30 minutes or so. It will come out looking like new.

Blow it off/wipe antifreeze away, mount the engine, install the prop, and start it up. What could be simpler.