Answer
If you live in a cold climate the thinner the oil the better so you might want to try 5w30 if on the other hand the climate where you live is warm to hot use 10w30 oil.
According to the 2006 Ford F-150 Owner Guide ( 5W-20 ) for all the available engines
The 2002 Ford F-150 Owner Guide shows ( 5W-20 ) engine oil
right above the left side of the oil filter
5w-30
summer: 10W30 winter: 5W30
According to the 2004 Ford F-150 owners manual : ( 5W-20 ) engine oil is used in the 5.4 liter V8 engine
Five quarts, including the quart in the oil filter when it is also changed.
5W-20 , according to the 2005 Ford F-150 Owner Guide
5W30 , according to the Owner Guide
The 2001 Ford F-150 / 4.6 liter and 5.4 liter V8 engines use ( 5W-20 ) engine oil according to the Owner Guide
Exactly the weight Ford recommends. Brand is your choice as all major brands are good.
5W-30 is the preferred oil ( that's what I've used in my 1995 Ford Explorer since 1995 )