They are real nice units. I would look for signs of leakage, soft lower radiator hose or bypass hose. The hoses deteriorate quicker on the lower end. It would be good to know that the coolant has been changed every 2-3 years, but no one seems to. The pump is at the lower front. The only head gaskets I've seen fail are those that ran hot due to being low on coolant. Oil should be oil, coolant should be coolant. Not cross habitation... Enjoy!