Shelf life of antifreeze?

[Pete]

Hi all,

I have a number of jugs of ethylene glycol antifreeze that have been in an unheated shed for years. During that time the temp has cycled beween -30 degrees to over 100 above. Some are name brand and some are mystery brand. Some still have an undisturbed original seal and some have been opened. A couple have been opened and mixed 50/50 with water according to the hand written scrawl on the jug. 

So is it okay to use this? I had a lot of work done to my cooling system last year and want to keep it in good condition. 

Thanks,

Pete
 

[Plymouthy Adams]

test it with a very inexpensive tester available over the counter at the big box store...