re capping

The Truth is available from the manufacturer.
Sometimes the Truth is optimistic and sometimes not.
Life is predicted based on science and math, but can vary widely due to variation in sub contractor supplied materials.

We once replaced 7 million 85°C/35V electrolytic caps with 105°C/50V version from another manufacturer. All was well for a while until we found that the replacement would fail if the bung was over the -18v rail. The potential sucked out the electrolyte and started fires once the electrolyte reached the positive rail.

Hey, same thing happened to the Quonset hut full of Volkswagen size non oil-filled capacitors the US Navy replaced oil-filled capacitors with on that secret communications project back in the 80s. They exploded. Of course the millions watts might have had something to do with it.  Lesson learned. 🤠

@hifiman5 

There are zero facts that support anything but what I said. I'd be surprised if you've ever looked at a spec sheet in your whole life. 

@kosst_amojan

Sorry you didn’t get the jest! A social comment by me on the societal status of "facts" and "truth". They are, as considered by the more progressive citizens, as fluid concepts. The many shades of gray!😮

Electrolyte is simply drying out.  Each 10degC temperature increase shortens the life of capacitor by factor of two.  Capacitor rated  60,000 hours at 25degC wil only last 30,000 hours at 35degC, 15,000 hours at 45degC  etc.  This can be found on many datasheets.

http://www.illinoiscapacitor.com/tech-center/life-calculators.aspx