Oil Can synthetic blend 5w-30 be used on a 2006 5.4L Ford F150, instead of the recommeded oil 5w-20.

Why not? Of course it can! What could happen to (any) engine because of that? A little bit worse (1 to 3%) fuel efficiency since 5W-30 is thicker than 5W-20! But, I'd ask you right now: Why you even consider synthetic blend? If you think that synthetic part (max 30%) in blended oil is going to improve mineral part you voluntarily admit that synthetic is better. USE (FULL) SYNTHETIC and have all the benefits - better mileage, extended drains, cleaner engine, better winter start, smoother operation... Want more? Why to waste natural resources if you can have simpler and better maintenance with synthetics? Do not forget good air and oil filters! They keep engine's longevity! If you want recommendation(s) - use Amsoil (XL oil for 7500 mi) or Mobil (extended). All others are (poorer) copies of them! For the filters - again Amsoil! Absolutely better than K&N! Same air flow and 50 times (!!!!!) better filtration. (If you need more info call 519-739-3765)