Shake it before using because it may have a small amount of compressor oil or sealant in it. Probably last for 15+ years but, one never knows for sure as some cans are coated with material and how long that lasts before disintegrating? Maybe ask the manufacture? Ed
I have some 20+ year old cans that are about to go on Craigslist or Ebay. I ran across a case of it cleaning up this last week and don't have any cars left that use it.
..........and don't worry about it. If it is there, it is good. It doesn't go bad in the can.