I'd say shelf life is comparable to its service life; 5 years.Does ethylene glycol-based coolant have a shelf life?
I have a gallon container of Prestone Dex-Cool approved 50/50 prediluted coolant (purchased late 2014). I've been using this 1-2 times per year to top-off the coolant in my 2014 Cruze. (I'm guessing I haven't used more than 16 oz. total.) Later on this year I'll be having the cooling system flushed.
Is it okay to continue using my existing Prestone coolant or should I buy a new gallon?