just bought a car needs some body work. Front end got hit radiator and overflow reservoir were both damaged. I drove the car and ran fine and I shut off right away (ust wanted to see it run. The head gasket is not blow. Just wondering why the coolant reservoir is half full with oil now and what should i do about it cuz im ready to install the new radiator and fill it up with coolant. Should I fill it up yet or what should i do first?