With the possibility of damage to the engine, I would not consider taking the risk, have it checked out to be sure. Better safe than buying a new engine. It may also come to pass that the cooling system will require some replacement of components due to their age. The plastic components of the radiator, the expansion tank and the thermostat housing have a definite lifespan and since you have an 12 year old car, I feel it is my responsibility to urge you to take action now to prevent a possible catastrophic failure of the cooling system and possible internal engine damage like a cracked cylinder head casting from even a brief overheating or an excursion into the temperature gauge red zone from a failed radiator or other cooling system component. I know this seems alarmist, but trust me it can happen, and don't ask me how I know that!
Saturday, February 14th, 2009 AT 7:14 PM