About a year ago I had a pretty bad leak I think was the head gasket. Coolant was trickling down the back of the engine and seemed to be coming from the block since there are no hoses or lines back there. No coolant in the oil which was good. I used a bottle of that blue devil pour n' go headgasket sealer and a bottle of K-seal and it is no longer leaking from there. For the $50 I spent on the additives I'm happy with the result.
I do have a slow mystery leak from somewhere else now. I thought it was the lower heater hose and replaced that. There is a braided hose near the water pump that I think is full of electrical wires that goes directly into the engine and I can see coolant dripping off of it. It is the highest point I can see fluid leak, so my guess is something is weeping internally and coming down out that braided hose. I tried another bottle of stop-leak and all it did was plug up my heater. Some days I have a few drips under the truck, other I don't. I just keep it topped off, and wear an extra pair of socks on cold days now.