I don't believe Dexcool is your problem. When was the last time you had a coolant system flush and refill? It should be done at least every five years with Dexcool. You need to figure out what the gunk is in your coolant system. I would start with a flush and refill and see where it leads from there, making sure the air is bled out of the system. You can also get some cooling system cleaner that you pour in after getting all the old coolant out. This cleaner will dissolve all the gunk. Then you flush it out and refill. You could have trans. fluid in your coolant system from a bad radiator, you could have an intake manifold leak, which would mean coolant in your oil, or you could have a head gasket leak, which would be blowing all your coolant out as you drive. You have to narrow it down.