Ford’s OLM is pretty accurate, taking idle time and heavy use into account. These motors seem to rid themselves of break-in metals between 10,000-15,000 miles, so I say run a 5,000 mile cycle once you’re past 10,000 miles and see how it looks. If oil life and performance seems to align with the OLM, then go from there. I see no reason to stray from 5W-30 or any brand that meets Ford’s specs unless a OLM suggests otherwise.
My experience has been M1 sheared below spec on my 1st gen EB, but there hasn’t been any increase in wear metals. I’ve run 3 cycles of Schaeffer’s full synthetic 5W-30 and wasn’t that impressed. Once I finish my current M1, I’m got a bunch of Magnatec to use.