I've been running Motorcraft oil in my truck since I got it. Great oil!
I've noticed with all of the Ford's I've owned is that they will tell you when they need the oil changed. Slight ping, the engine makes a little more noise. The one time I did NOT use non-synthetic oil in I noticed that I got 3k from an oil change, with Motorcraft I got 5-6k.
I recently changed to Mobil 1 about 3 months ago. I hit 100k miles and plus there was a sale at O-Reily as mentioned before in this post for less than $3.50 a quart, I bought a bunch too..
Since running Mobile 1 I've noticed my engine running smoother, quieter, especially during start-ups. I plan on a 6-7k mile change interval with Mobil 1.
If and when I get a new F-150 I plan on using the MotorCraft oil again. I'm just noticing for my high mileage truck (that is well broken in) a full synthetic makes a difference.