I'm not a good judge of bearing life for I have too many engines to use any one much. The bearings I have replaced were in engines that had bad or marginal bearings when I got them or the engines belonged to others.

I generally use Omega fuel that has a little castor.

I did have an engine to jell up on me from castor oil when I had to move away and it sat for three years with no after run oil. I replaced the bearings.