Brad Penn 20-50 for me.
I was using redline 10-40 never again rod bearings looked terrible mains were ok. Been building engines for local racers here.
One customer was using Brad Penn 20-50 oil when we torn him down for a freshen up all the bearings look like we just put them in I was
sold on Brad Penn after that.
Used valvoline racing oil in the old days
no issues bearings looked good but that was in the 80’s before the EPA made the oil companies to reduce zinc content.