According to the manual you need to use 5W20 and it needs to meet the Ford spec. Technically, if your engine were to blow up during the warranty period, they could deny your claim if you had Mobil 1 5W30 instead of 5W20. The Ford spec also has a fairly different additive pacakage requirement than traditionally used, so I am not sure if even Mobil 1 meets the spec. Probably, but not sure.
This is very unlikely, that the engine would blow, especially if you change your oil regulalry, almost not mattering what brand you use.
I use 5W30 Mobil 1 in my 2004 LS V8 which is still under warranty. I am willing to bet I never will have a claim on engine damage due to using Mobil 1 in the crankcase, even if it is the wrong weight.
One thing I noticed was that when I changed the oil at 15,000 from the assumed 5W20 blend used by Ford to Mobil 1 5W30, the engine had far less startup clatter than the blend had. Something like 3 seconds versus just a blip. It could also be the difference in filter used. The original filter was Ford, the replacement was Fram, yes yes I know, but it was the only brand I could find that fit then. I now have Wix.
I guess we will eventually find out if using the wrong weight Mobil 1 will kill my engine, but I bet it takes years and years before I know.
Jim Henderson