Toyota Camry 2004: What coolant should I use?

There’s no problem about buying a generic brand of coolant off the shelf and filling the system, just make you mix it to the correct ratio. It is a good idea to replace coolant at times and it might well be worth doing that at this time of your wife’s car. Before doing anything, however, inspect the cooling system for leaks that might have caused your wife’s car to lose coolant.