Coolant Question - Can it degrade or go bad?

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I have quite a few coolants laying around, some of them are sealed and some are open.

Was wondering if can go bad after some time or have some expiration? Understand, it's NOT milk.
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But still wanted to verify with pro's Thank you
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It never goes bad.

I have drained "near-new coolant" from rusty systems, let the crud settle down, and put it right back in another system.

Coolant never "wears out" - Several engine manufacturers suggest doing an analysis to see which additives are depleted (similar to a UOA) and the additives can be bought separately in small bottles to add to the coolant to replenish it.
 
I read a long time ago that its the heating and cooling cycles that cause the additives to deteriorate, it sounds reasonable but I have no idea how true it is.
 
So does it mean it'll go bad in 'opened' bottles and should be good in sealed bottles?

Thank you all.
 
Valvoline lists shelf life for their Zerex brand antifreeze products on their web site, in the PI sheets. I use those as my go-by, it varies from 2 years to 5 years depending on specific antifreeze type.

You could call or email Valvoline to get their viewpoint on what happens when antifreeze shelfife is exceeded.
 
About 6 years ago I put traditional green Zerex made in 1998 (from an unopened container in my garage) into a newly purchased (used) 2008 Hyundai Elantra. When I changed the timing belt 2 years later the water pump looked brand new.
I don't think unopened coolant deteriorates over time enough to worry about.

PS: None of the coolant had settled out in the container despite sitting all of those years....
 
Yes it degrades and can go bad. The inhibitors do break down and don't protect metal as well as fresh AF. Also Coolant becomes Acidic and corrodes metal. To stay on top of the game...you can always buy test strips and check your fluid every year.
 
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