Need help with oil leak that started while pulling RV

[90dfw]

03-F250 4x4,89K miles.
My GF's Dad was pulling his Camper yesterday and next thing he knows he is sending a Mist of oil out the back of his truck..He was pulling it thru Hilly terrain and it was VERY windy. Said he lost power like the turbo gave out then it picked back up again. He pulled over and noticed that the front of the rv was covered in a mist of oil. looked under the truck and it looks like it had been armor all'd..
I looked at it this morning and Found that when idleing there is a constant drip coming from the TOP Rear of the engine. You cant see it from above but if i crawl under the truck and look up on the driver side between the tranny and engine I can see the drip. Im thinking it might be a turbo oil line,but I have no experience on Powerstrokes. I have a cummins.
The oil was changed on wed,and drove fine with no leaks,no problems untill he pulled his Rv.
When he starts the truck up, it takes a few seconds for the oil pressure guage to show any pressure,where as before it was almost instant. Im thinking it might be because he is low on oil, but he is afraid to add anymore because of over filling.
He is extremely anal about maintance and changes all the filters before the scheduled time.He has also owned the truck since new.
Right now the truck is sitting in his driveway and this is his only car, can any one help??? Thanks.