OH this wasn't answered.
So the more power a motor makes the more load on the crankshaft and thus the bearings etc. SO for people that have never taken one apart something most don't know. The crankshaft of a car engine - sits on just oil. There are bearings that are basically special sleeves. they cup the crank journal (a highly polished area) on the crank shaft. and they have grooves and a hole or 2 - which is where oil pressure fills the gap and "lifts" the crankshaft off the bearing.
Now I put that in quotes because in some cases there is a lifting and in some cases there is not. and it's very complicated maths that make this work. But oil pressure, and viscosity, and density is all part of that complicated maths. As the oil heats up it's density and viscosity tend to fall down - which could be a bad thing on those crankshaft bearings.
So as an engine makes more torque - and as it runs hotter - those redline runs under load etc. are one of the places where you check your math. And decide with X surface area, and Y density . . . . . . . - I can support _____ lbs of force on the bearing. vs - piston face, cylinder temp, crank arm, pressure of combustion . . . . creates ________ lbs of force on the crankshaft. you want both ________ to be equal or the bearing to be > the shaft load. SSo the ecoboost mill makes more torque than the Ti_VCT mill - pretty easy to see - as such it runs hard in those higher RPM's. So it needs a higher viscosity equivalent to keep up the crank bearings and probably other things like piston rings and the cam journals. (there are a few other places in the engine design where you check your maths too)
More torque mills tend to use higher viscosity oils. Diesel motors - some of them anyway - use 15W40 or 50.
so yes the ecoboost mill needs 5W30 - easily - if you modded it and ran it in hotter climates I'd seriously consider putting 10w30 or 10w40 in it. ALso for the turbo.