It looks like lifetime is specified in hours of life at a high temperature - e.g.:

http://www.rubycon.co.jp/en/catalog/e_pdfs/aluminum/e_BXF.pd...

Lifetime is specified at 10000hrs at 105deg C.

As temperature decreases, lifetime appx doubles per 10deg C:

http://www.low-esr.com/endurance.asp

It looks like a cap rated at 4000h @ 105deg C should last around 60 years at 100deg F or so. Anecdotally I have a guitar amp made in the 60s with the original electrolytics still working. Sounds great.