The 2012 R/T shipped from the factory with conventional non-synthetic blend. After the first service required oil change (break-in period) you can continue to use conventional oil, synthetic blend or full synthetic. I use full synthetic. The only requirement for MDS is 5W20 viscosity oil.
There is a lot of propaganda regarding synthetic oil and while some of it might be true it is often very exaggerated.
Having said that the one thing that is NOT stressed enough and is 101 percent a plus is the cold weather benefit.
Take a quart of conventional oil 5w 20 ( any weight conventional really) and put it in your freezer for two hours. Take it out and shake it. You will feel how it really thickens up and the higher (numerically) number the thicker it gets. Sae 40 for example would become almost like a thick syrup.
The 5w 20 conventional still gets thick in the cold. NOt as bad as SAE 40 or Sae 30 but thick enough none the less.
Now take the 5w 20 Full synthetic out of the freezer and shake it. You will see it is still very fluid.
Now think how that equates to your engine. You oil pump will love it in the cold startups. That's really the biggest benefit. The cold startups.
I have a 7.3 powerstroke excursion too. Before running full synthetic when it got bitter cold in the morning like zero of lower I would have to plug that bad boy into the wall the night before to warm the oil. Changing to full synthetic it starts just as easy at zero degrees as it does at 50 degrees.
I see you are from NY...which I assume is New York, USA.
The full synthetic is what I would run if I were you.
Not going to get into that horeshit.
They are all good. Even the in house brands are good. Find what is on sale and go with it. Full synthetic benefits are less in warmer weather. MIght you eek out a half a mile per gallon more? Maybe. Does it really coat your engine compontents...maybe.
But there is no doubt whatsoever the cold weather start up benefit. That part is just fact.