You are talking about two or three different things. If there is any green or yellow antifreeze present from the oil filter/cooler housing the cooler is bad. Remove the filter and pressure test the cooling system. If ANY coolant is present at the oil filter mount........... do not drive the truck until you get a replacement oil cooler assembly.
The muck in your cooling system is you oil getting into the cooling system. I would be more concerned with water getting into you oil system.