[ckelly78z]

One of the big problems of the Ford 6.0L diesel motors from 2003-2007 was the coolant they used. The "Ford Gold" coolant would crystalize after a period of time which would block the tiny passages in the oil cooler, and EGR system. This would increase the pressure in the head which would blow the head gasket/stretch the head bolts, and ultimately wash down the cylinders with coolant.

It was highly recommended to change out the factory coolant, and completely flush the system to get rid of any crystalized traces before any problems were discovered. It was also good to replace the stock head bolts with head studs (which don't stretch), and the head gasket while apart. Many eliminate the EGR cooler, and change the oil cooler as a preventative. (Bulletproofing).