does aluminum spool wire have a "shelf-life"?

Sealed rolls, or what's been sitting in the gun? Depends on how it has been stored, humidity, shop environment with airborne solvents, airborne paint fumes, exhaust fumes, several factors. All aluminum is notorious for oxidation, and it oxidizes rapidly even in good air.
Look at it. Is it sealed inside plastic? Mainly look for white powder. That's the oxidation you don't want. If it is a critical application, you might want to start with new wire. I'd try some test coupons first. CAREFULLY open it up and tie one end to something. Put a dowel through the center holes and walk until about 10-20 feet come off. Have an assistant help you. One hold the spool and dowel. Take a dark rag and run down the cloth pinching it between two fingers and look for white on the rag. That should tell you a lot if there's some there, just not visible through the plastic. If that comes up clean, I'd say it's good to go. If it's white, you got oxidation. Carefully respool the wire by turning the spool and not wrapping the wire around the spool. Do it carefully because if you kink it, you might want to just toss that piece. If it's noncritical, and there isn't obvious excessive white powder, I'd run it if I got some good coupons on test welds. Band saw coupons to look inside.
HTH
Steve

"Steve B" wrote: (clip) All aluminum is notorious for ^^^^^^^^^^^^^^^^^^^^ It is true that aluminum oxidizes almost instantly after it is cleaned. However, the thin oxide film that forms protects the Al from further rapid oxidation. Chances are your spool of wire, if it has been kept in a sensible indoor location, will be just fine. I would go ahead and try it--you can always replace it if you find it necessary. Your work is also going to be covered with an oxide film. That's a fact of life with aluminum.