Another thing to consider is the reformulation of the fuel we use.  It used to be gasoline.  Not so much anymore.  Ethanol is what trashes the original “rubber” lines I’m told.

Jim

> On Aug 18, 2017, at 9:45 AM, Stuart MacMillan <stuartmacm@GMAIL.COM> wrote:
> 
> They are better quality, and another thing is that ozone and NOx levels in big city air was much higher in the '80s than it is today, both of which attacked rubber.  I don't expect to replace these seals again in my lifetime, but I'm old.  Still, I'd expect these to last at least another 30 years if not longer, since they are not exposed to UV, and modern synthetic rubber (EPDM) is very stable and long lasting. It's even used as roofing on flat roofs and has a 50 year warranty in that application. 
> 
> Stuart