More than likely, you are going to replace the radiator in your vehicle at least once. The joints where the cores meet the end tanks tend to get weak and are the first place to spring a leak. Impacts to the fins themselves can cause holes to form. Corrosion and clogging from the inside can make cooling less than effective and compromise coolant flow.

Replace your leaking unit with a factory replacement and get that jug of coolant out of your back seat.