Making Sense of Synthetic Lubricants
Just an opinion but I've heard the same from most engine builders...conventional oil can 'start' breaking down at 230-250 degrees and oxidizing.
Semi syn and synthetics have higher temp ratings but even a semi syn is pushed at 250.
Many of us use semi syn oils like B Penn etc for the higher zinc for our flat tappet motors.
In a newer car with hyd tappets and a fully syn oil you'd be ok I suspect.