You really won't be able to recognize a difference in going with the lighter oil especially living in the south. As for warranty, you have to go with what is in the manual, if it calls for 5w30, use a 30W and be happy. I would go with 0w30, that won't void any warranty. I think PP 5w30 is one of the better off the shelf oils IMHO. I would recommend that at the OEM OCI. I can't imagine it is 3k miles though.
You really think that 5w20 wont give me a little better gas mileage?
Does it allow for 5w20? If not then use 5w30 only. Thats surprising though that such a new car still uses 5w30. If I were you change out the FF at 3000 miles, then do a run or two of 3000 mile OCI's with PYB, then go to PP for the life of the car.
Thats what I was thinking, I want the engine to break in properly, Ive heard not to use synthetic oil in a new engine because it wont wear properly, but then again I heard that GM vehicle use Mobile 1 as their factory fill. I just want the best fuel mileage and protection without voiding warranty and possible grenading the engine.