I was at a garage sale the other day. A guy had some 4 litre jugs of antifreeze sitting on a shelf and I asked him(jokingly) if they were for sale. Well, to make a long story short, I walked out of there with 2 full and 2 almost full jugs of coolant for $1. I'm willing to bet that all the jugs are a couple of years old. The two open jugs look to be pure antifreeze. It looks and smells ok, but can coolant breakdown over time? What about the sealed bottles? Is there a shelf life I should be aware of? Sorry for the dumb question, but I don't believe this has ever come up before.