Well, I had run the motor on 15W-50 Mobil1 since the day I got it. I had switched to a lighter oil (Royal Purple 10W-30) and your logic could be correct. From the cran;, rod and block carnage, it looks that a bearing seized and caused the boom.
On a side note, my old motor had a lightweight flywheel and 3 puck on it. Never knew lol. I still love my OS Giken. I am finally getting the hang of it, but damn starting from a standstill is a b|tch.
