you could try to pressure test the cooling system. it's like a little bicycle pump with a gauge on it, build it up to 15psi and watch to see if it holds pressure. if you really had it running for almost an hour and it was leaking, you probably would have spun a bearing by the end of it. also could be any assembly lube you used putting it together. change the oil regardless, and if you have some extra cash, take it to a shop for an engine flush. its what we do after all the 3800 lim gasket jobs lol
