Question About Engine Oil

[Kaotic Lazagna]

Okay, I changed my oil and had a little left over. So I decided to bring it up to my room and put it in the corner only to see that I have about a quart of Amsoil in a gallon container sitting there. Now my question is, this oil has probably been sitting in that corner of my closet for almost a year (my last oil change was October 28, 2008 (been running Amsoil with the EA oil filter), and the bottle has been opened (but closed tight, but not taped around). Can I still use this oil? It does not appear to have condensation on the walls of the bottle. Or is it useless now? I'm not running an EA filter this time around, so I'll be changing my oil filter (WIX) at the next 5k miles. And since there will be some oil taken out with the filter, I'm going to need to put some in. So it would be nice if I didn't have to buy another quart of Amsoil since I have some already. TIA.