what is is working best w/ these engines? i running chevron 5w20 now but the stash is gone...was thinking redline or royal purple or torco...any input would be greatly appreciated....
If still in warranty stick with what Ford recommends. As for me I go with Chevron Supreme 10W-30. It is what I use in my 98' F150 5.4L and in my 2003 Camry with a 2.4L 4 cylinder. For that matter Havoline is just as good in the same weight.
my 03 5.4 seems to like Schaeffer's 5w30, but it has only been in for about 2,000 miles. I will change it at 3,500 for the first interval and have an analysis done. I will post my results to let you know how it held up.