Apparantly I am "oil illiterate" becasue I took it back to the shop that did the exhaust today and they put it on the lift and it is engine oil. The guy said it did not appear to be the rear main seal and speculated that it is either a valve cover or a turbo seal.
Does that mean anything to any of you and how hard would either of those two things be to fix, I am a fair mechanic but a rookie at diesels.