What oil for my new engine

I've been using older, conventional racing or diesel oils for break-in. With flat tappet cams, I use to put either OEM springs on or remove the inner springs from dual-spring set-ups for break in for insurance. It's a lot of work, but for me it was worth it. Right now I have a couple of sets of Schubeck lifters which don't require break-in.

After break-in, I use one of the lighter Amsoil motor oils with corresponding tighter clearances. Many of them do have high concentrations of zinc for long term protection. My engine builders over the years have noticed less wear with Amsoil over conventional oils. There are HP benefits too.

High zinc Amsoil synthetics:
https://www.amsoil.com/dealer/techservicesbulletin/MotorOil/TSB MO-2007-08-08 Flat Tappet.pdf

Amsoil source & info:
www.thelubepage.com