If you haven't found Black Diamond's Quailty lab, enough the next few hours. They did a test on old ropes a while back.

If you look at manufacturer they give you a lifetime suggestion based upon use for all soft gear. 

WeightMyRack has a sweet graphic based on years and frequency of use

 

Back to personal opinion, I agree. If you don't trust it, don't use it. However, I've eeked out a few more months and years from rope by doing an inspection and then having a friend do an inspection and talking about it. At very least you can demote this rope to top rope only for when you have friends.