Coolant (antifreeze) is a complex chemical liquid helps prevent freezing in cold climates, so that cars can operate in sub zero temperatures, and boils at a higher temperature than water. Besides this, it also lubricates the water pump as it flows through. Some antifreeze compounds are specially formulated for aluminum radiators. Keep the coolant somewhere between 20 and 60 percent of the mixture in your car, depending on the car and climactic conditions. If your car is leaking in coolant, It might be leaking in small amounts from the heater core into the passenger compartment, or the water pump may leak. It’s also possible the car loses coolant only while it’s running, which would make a leak harder to spot. Have a mechanic pressure-test the cooling system, check the head gasket, and inspect the water pump. Do not use a strong antifreeze mixture as it can cause leaks in your car’s cooling system. Coolant is extremely poisonous and should be handled with care. If it spills on the ground it can kill stray animals that drink it.