I work on A LOT of the 6.0's and 4.5's which are the V6 knock off in the LCF's.... I've had to replace 3 intakes to date due to the massive amount of carbon build up in the intake manifold and EGR valve... Couldnt clean it well enough! If you are having to add any coolant you better think about replacing the EGR cooler along with the oil cooler as the EGR cooler is supplied with coolant from the oil cooler. Usually the oil cooler will become restricted and then starve the EGR cooler causing it to crack internally... I've had to do ALOT of oil coolers and EGR coolers in these things as well. Best way to test if the EGR cooler is leaking is to pressure up the coolant tank, jack the rear of the truck up and remove the EGR valve and take a peak inside. You'll know if its leaking.
