Warning to new owners!!!!
While I would agree with you to a certain degree. Bearing tolerance is very critical to a oil choice. However the difference we're talking when switching to something like a 5w30 or even 10w30 isn't all that different. A good friend of mine is a oil engineer at a fairly large oil company that primarily deals with motorsports and automotive oils. My last car a 4.6L 3V S197 spec'd 5w20, which was actually designed to run 5w30, but I ran 10w30 under his advice due to the high hp application and the lack of cold temperatures in Florida. A lot of oil specs that the manufactures put out there have one thing in mind, mpg and CAFE standards.
Keep in mind that Ford also has to consider all of the environments a truck will be used in when they make an oil recommendation as well. I like in an area where it can hit -60 degrees-I would never consider using 10w in my vehicles.
If I lived where you did I'd be using a 0w something true synthetic such as Amsoil Signature.





