The problem, as I understand it, with this engine, is that it churns out a lot of muck. The EGR valve recirculates exhaust gases, complete with all the soot left over from the combustion. This builds up a residue in the manifold and EGR valve itself and gets in the oil. The sooty-oil clogs up the Turbo oil feed and pickup pipe which in turn starves the turbo of lubricant and when that fails, as a result, the whole thing gets well expensive. This is all compounded when the EGR valve, itself, gets stuck because its cloogged up and stuck open.
I'm advised that low soot/ash oils are a must and a regular oil change is very beneficial. My advice to anyone is get the Manifold and EGR valve cleaned out if it's never been done. Do an oil change every 3 months ( depending on use ) and check for injector leaks ( Hold your hand over each injector to see if there's exhaust puffing out ).
And most importantly, get someone who knows what they're doing, to do it all.