I have a 2004 Ford F150 with a 4.6 V-8. I'd like to know the proper amount of oil to put in it. The owner's manual says 6 qts but with 6 in it, the level is low. I have to put a good 7 qts in it (just a tad over) to show full on the dip stick. Which is correct? I remember years ago Ford had a "dip stick" issue. The dealer even cut a hash mark in my Dad's Truck when it was new due to the dip stick not matching the owner's manual (1989?). Thoughts..