if the difference in price is not that significant, i would opt for a new radiator. today's age, men tend to marry somebody with baggage already from a previous relationships, this makes the situation complicated. for me, if i intend to keep the car for sometime and not be paranoid about breakdowns, i would install a new part. the used (commonly called surplus) radiator may already have calcium buildup or the outer surface of the cooling fins partially corroded or the metal fatigued.