Bought the car today, Test drove it, Everything was fine. Get 20 minutes down the road and it overheats and shuts off. Let it cool off and put water and oil in it and got it the 2 more miles home. After letting it cool off and filling it completely full of water I let it idle and there it a leak coming from somewhere *I think it's the lower radiator hose* it's not just dripping it's pouring out at a pretty steady stream. Anyway, What I am getting at is...Since their is oil in the coolant is it pretty safe to assume the head gasket is done? Or what else could it be?