Ever have a sweet smell in your car coming from the vents. or is your heat not a good as it used to be. these thing can be attributed to a clogged or leaking heater core. we recommend changing the coolant in your car every 3 to 5 years. in doing so you will be adding fresh rust inhibitors and once again have the recommended boiling and cooling temperatures. remember maintance now will save from expensive repairs in the future.