The Ford 6.0L engine has gotten a bad reputation over the years as being unreliable and prone to failures.  The good thing is that there are upgrades available from quality aftermarket companies like that go a long way in fixing the weaknesses in the 6.0L engine.  A common failure in the 6.0L engine is the EGR (exhaust gas recirculation) system.  Part of the exhaust gas gets routed back through the engine to be burned a second time and therefore improves the emissions coming out of the tail pipe.  The EGR cooler has engine coolant circulating through it to cool the exhaust gases going back into the engine.  The EGR cooler is prone to cracking and leaking coolant into the engine causing smoke, or if bad enough, it can cause major engine damage.  The problem lies in the thin fins that the coolant circulates through.  Those thin fins can crack from overheating due to a lack of coolant and or excessive exhaust gas temperatures EGT’s produced from performance upgrades.  The excessive EGT’s is easy to figure out, but why would there be a lack of coolant?  The answer is a plugged oil cooler.  The oil cooler works much like the EGR cooler.  There are thin fins that circulate coolant through the oil cooler.  Engine coolant will get contaminated over time with deposits large enough to plug up these fins.  The EGR cooler is downstream from the oil cooler and can also be clogged from contamination, but when the oil cooler plugs up there is less coolant flowing to the EGR cooler and the EGR fins overheat and fail.  By removing the thin fins and replacing them with high flowing tubes that withstand higher temperatures, and do not plug up like the factory coolers do, the EGR cooler problems are solved!  Upgraded oil cooler systems that do not use engine coolant to cool the oil are now available.  These oil cooler systems allow the coolant to go directly to the EGR cooler, and when using the upgraded EGR cooler, the clogging problems and leaking problems are a thing of the past!