Just remember that I'm *not* an expert(heck, I don't even play one on TV!
) on any of this- just "long term interested".
Since warranty coverage is a concern, then my advice is to stick with the oil weight they recommend, at least until the warranty is up.
If something bad should happen to your engine, no sense in handing the other side a bone of contention.
I don't know about any smaller holes/passages for the oil, but it sounds suspicious to me- sort of like the claims of different engine clearances for different countries.
Among other things, my brother claims he recently ran some SuperTech synthetic oil in his 4.7 L Durango for over 25,000 miles- and knowing him, it was probably 20w50, or at least 10w40.(do they make a ST syn in 10w40?) He's now running Havoline Synthetic 5w40 in it and it's doing just fine.
For OCI's of ~4K, IMO there's probably no advantage to running 10w30 over 5w30. Theory says that 10w30 should be more shear stable, but these days that may be more "on paper" than "real world"- Havoline 5w30 has produced some excellent UOAs.
In short- stick with 5w30, drive the dickens out of it & don't worry.