I know when we buy mono line from a tackle store of a deparment store, we have no way of knowing how old that line is. It could be a month old or 2 years old. I am very picky about the condition of my line, I mainly use berkly big game, and change line on my reels several times a year. I do buy my line in bulk, and have alot of line left over from year to year. I store my spools of line inside, in a dresser drawer, out of the sunlite of course. The conclusion that I have made is old line, as long as it has been stored right is fine to put on my reels. The biggame line I spooled some of my reels up this year was 4 years old, "now I would never leave line on a reel that long". After using it a couple times this year, the line casted fine, and when I got hung up on a big snag it took a whole bunch of pressure to break it off, so I could not tell of any loss in strength. So I feel as long as you store your extra line out of the sun, out of the summer heat and inside you will be fine using old line. Now my feelings may change if my line snaps on a big flathead this year:wink: But I have been using old line for years, "I buy alot at one time" and it has worked just fine.