Oil in coolant 2.8QS

[Ronin]

Hello

My A8 is getting oil in coolant but its not overheating and never has even on 250 mile trip of non stop driving.

My mechanic tells me it has to be headgasket and wants to pull the engine apart and re do it all which is crazy expensive..

I've looked on forums and its possible that it may be just the oil cooler.. the engine also intermittenly smokes from just about where the oil cooler is and it smells of oil too..

Am I being too optimistic or is my mechanic just looking to top up his retirement fund?