The right head gasket is leaking lots of oil around the back edge just above the starter. I leave a big smoke trail from the oil blowing down on the converter. I used lots of cleaner to isolate the source. I initially thought that the rear crank seal was the problem. It is OK. The 4.6 is the Windsor design. Is this a common problem? With the overhead cam, the head has oil pressure paths for the cam bearings.

 

Common? Ya, pretty much. Mine's been doing it for years, super slow leak but mostly in the blocks valley, driver side head. One day I will replace the head gasket to ultimately solve the problem but it actually seems to have stopped.