almost the same **** happen to my gf car.. i put in that "stop leak" stuff and later on the radiator blew up..the upper plastic part cracked. so had to get a new radiator(got a dual core all metal one at radiatorbarn.com) it run good now but i think the themo and fan is f ck up in the car. but since its pretty cold here so i didnt replace it yet...

oh yeah the smoke...i think its the water/coolant boiling up and spilling out from the radiator (that what happen to the car) white smoke/steam or it got f ckin hot and the oil burnt (gray or black smoke??)