Ive been using Mobil 1 in all my vehicles over the last 10 or so years and it has never let me down either. The thing is, Amsoil is so expensive. Really though, i know that it is better and all that, but if something else is working fine then why throw money away on fluids?
Hell, i used to use regular old Valvoline in my 347ci Stroker engined Mustang for 8 years and never had any issues. When i sold it, the guy swapped a Ford big block into it( i want to say 460?) When he sold the 347 he said it was in immaculate shape.
I really do not think we HAVE to use killer oil in our trucks as long as we change the oil and filter when we are supposed to. I just put whatever is the cheapest oil at wally world in the wife's 2007 Corolla S. Been doing it since we bought it new. The oil doesnt even look hardly dirty when i change it every 5000 miles. She's at 90k miles now.