With the extensive testing Ford did prior to recommending 5w20 in many of their engines, the 4.0l SOHC V6 in the Explorer was one of about three or four engines that Ford determined did not meet acceptable limits for enegine wear using 5w20. Thats why it still has the 5w30 recommendation.
Al - that is not correct, as F150's use 5w20 in all engine sizes. CAFE also applies to light trucks, currently the standard is 20.7 mpg. Even the 4.6l in the explorer uses 5w20. While it may be a CAFE issue, Ford not using 5w20 one engine in their light truck line up doesn't mean that all light trucks don't use 5w20.
Ford does not print charts in it's manuals anymore recommending different grades for different temps. It is one recommended grade only.
The musting v8's do use 5w20, inlcuding in the Cobra versions. I believe the Cobra R, which has a 5.4l V8, uses a different grade though.
For all of the hesitation by folks on this board who are supposedly open minded when it comes to oil, folks sure are afraid of 5w20. I still haven't seen an oil analysis that shows bad numbers on 5w20. It's been speced for over two years in F150's, and there has not been a rash of engine failures from users. I still haven't seen a great arguement that says 5w20 is bad.
But then I use bad old 5w30 in three of my vehicles, and have used it since 1989... and I have two of them pushing 200,000 miles with still no oil consumption to this day - go figure...