I made a thread awhile back about chemical flushes, and didn't get much of a consensus. My truck needs a cooling system overhaul which will probably include a new radiator & water pump as well. What I need to know though, is how do I clean the block? How do I get what looks like oily, nasty coolant out of the block? I have a feeling at some point in this trucks life DexCool and green got mixed, but I can't confirm. It leaks a little bit of coolant and I have to top it off every few weeks. It's NOT burning coolant, it's just leaking it. Any ideas?