Priobe,
You have bypassed the filters and thus bypassed the external relief valves. I read your posts a couple of times but may have missed what cold start up P was. What is cold pressure at idle and say 2K RPM? I see you live in Miami so it is plenty warm there and could be thinning
oil with heat a bit. If Pressure cold is OK I would try straight 50 WT and check at operating temp. If a big difference then a lot of suggestions. This pressure at
oil temp of say 230 to 250 degrees on a stock pump would be normal with 30W of the 10w/30W. Hope it is an easy fix.