I have a 2014 Mustang GT with the 5.0 that I bought new. I've used Motorcraft 5w-20 and a Motorcraft filter since the beginning. Since It's my fun car and I don't drive it daily, I change oil once a year. Car only has 27,000 miles on it and the least amount of miles I've have done in a year has been about 2,000 and the most about 7,200 miles.
I broke my car in using some pretty hard acceleration runs and then letting it engine brake it self down. I did this several different times. My car hardly uses any oil at all.
This is my first new Ford vehicle and because I've had several issues getting warranty work done on this car, I choose to use Motorcraft parts and the recommended oil viscosity at least until the drivetrain warranty is up in August.
Have fun with the new car, it's a beast.
Wayne