7 here's why....... quote from a Ford R&D Tech......
"When at Ford, we ran with clear pans, windowed front covers and cam covers. The oil under high rpms gets slowed in the heads, the front cover and the front of the oil pan.
As the chain drives the cam system, the oil is trying to get down thru the cover area. Also the area around the front of the pan shares space with the oil pump and pickup tube. Oil is tryig to get back to the pan and everything is in the way.
The drain back holes are the same between 2v, 3v and 4v.
Ford conducts a WOT test for 100's of hours.
On the street you don't see consistent 6,500+ runs. On the track, I suggest you add 1 qt. Adding 1 qt does not over fill the pan to the point that the crank or rods run thru it. When at idle, you're 2 qts low anyways."