My 2004 Super Crew is leaking oil at the rate of about 1 quart every 300 miles. There is fresh oil residue from the front of the oil pan and back as well as minor oil residue on the timing cover and several of the pulleys. I suspect it is leaking either from the crank seal or the oil pan to timing cover interface directly underneath the crank pulley. I replaced all the timing components back in May 2012 (@95000 miles) but have not driven it much since then. I recently took it on a 600 mile trip and had to add a quart before I left, a quart when I got to my destination, and another quart upon returning home. Here is what I know and have done so far:
(1) After replacing the timing components in 2012, I changed from Motorcraft 5W20 to Mobile 1 5W20 synthetic.
(2) There has been no noticeable oil residue on the ground at all.
(3) Removed the radiator fan and shroud, cleaned everything up and ran it for 20 minutes at about 1500 rpm - there was no visible oil leakage from anywhere.
(4) checked the torque on the front oil pan bolts which had to be loosened to remove and re-install the timing cover back in 2012 - they were all at least 15 ft-lbs. I did use gasket sealer on the oil pan to block joints when I re-installed the timing cover.

So it would seem that movement is required for this leak to occurr. I calculated that 1 quart every 600 miles is about 1 drop per second. I really expected to see something over a 20 minute run however.

So is there any better way to diagnose where exactly the leakage is occurring or is it just a matter of fixing one and seeing what happens?

 

Most likely source is the front main seal. Also, it is widely known that changing to full-synthetic on well-used engines has been the cause of oil leaking from every seal and gasket. Motrorcraft synthetic blend is all the oil you would ever need.