Overheating is a major issue when it comes to vehicles. That's why it's important to monitor the temperature of your vehicle. It shouldn't go to dangerously high levels or else it could cause extreme damage to your car. One of the things that help keep a vehicle cool is putting a coolant in the radiator. The downside is that you need to additional cash outlay for coolant. Currently, I just put water because the hose has a leak. I don't want to waste coolant. Do you put coolant in your radiator? Or do you just put water?