The root cause of the egr failure is the coolant circuit of the oil cooler clogging up and starving it for coolant making the brazing melt inside the egr cooler and leak. The oil cooler clogs due to the coolant/casting sand whatever you want to call it. Coolant does double duty on diesel motors and must be changed more often than 100k as origionally advertised. My personal experiences are from working on them at the dealership. My boss had one, now owned by his dad. Drained and refilled coolant every 30k and no problems with the truck. His brother has a newer 6.0 and did no maintenance other than oil changes and began having all kinds of problems at 80k miles. I do like the tube type egr cooler though the look like they are welded at the ends and not brazed.