The thin oil is probably why the oil pump lost it's prime sitting.
There was a post lately discussing motor oil, and saying Cub engines aren't designed to use the modern thin oils. The clearances in the Cub engines are too big for the thin oils, like the oils with weights beginning with 0.
The 15W40 weight oil is good, people on here use it.
The Cub still looks good in your pictures.
