What is the Shelf Life of Radiator Coolant or Antifreeze?

It's been asked many times, so we went to the radiator coolant experts at Prestone to find out the shelf life of a bottle of coolant. It turns out your radiator isn't too picky how old the coolant is, because a gallon of the stuff is good for years. Even if the bottle of radiator coolant has been opened, it's good for years.

This means there's no good reason to postpone a radiator coolant check or perform a seasonal radiator flush so that your car's radiator will perform correctly and last for years and years, just like a bottle of coolant.