How long does shortening last before it goes rancid? & do you guys just store your tubs in cool areas such as the basement?

I bought some sweetex and I had an unopened tub and an opened tub in my pantry closet and the opened tub seemed to smell "different" so i just use that for practice icing & decorating because i'm scared to eat it lol. I moved my unopened tub to my basement with the rest of my cake stuff but do you think that one is ruined as well?

How long has it been in there? I have kept mine for quite a while and it was fine. Before I started really cake decorating a large tub from Sam's would last me at least 3 months, but more like 4-6 months (now they still last me 1-2 months). The "best by" date on the one I have now is June 2011. I would say if the date is still good it should be fine.