I have seen it also but have not used it.
I took my wifes Mustang in for an oil change the other day, it had 5w20 in it but only had about 1100 miles since the previous oil change, didnt matter I wanted the light oil out of it now that warmer weather is here so in to Ford she went. Pick it up half hour later and say thanks and get in the car and leave. I'm almost home and I look at the window decal and the goofy idiots put 5w20 back in it again... Im thinking ***!? So I pull it in the garage and go through the paperwork from the change to see if maybe the decal was just a typo. Nope, right on the work order it says that 6 qts of 5w20 went in the pan. Now I'm a little hot but before I call the dealer and rip some tail I wanted to check the owners manual, instead I popped the hood and right on the oil fill cap it says 5w20 is the recommended oil in the engine.
Seems light to me, not sure what the difference is on this engine. It is the modular 4.6L so that may be it I guess?