Rebuilt engine initial fiasco

Unless you have .003 bearing clearances or larger, why would anyone run such a thick oil anyway?
Not trying to be rude, I just don't see the need. I run my bearings at the tighter end, just shy of .002 and run no thicker than a 15/40.

I put in what the machine shop supplied and wanted me to use. Lucas high zinc engine break-in oil 20w-50