typical "shelf-life" of phono cartridges?

Just wondering if there's a rule-of-thumb for the useful shelf life of phono cartridges.. I bought an fairly inexpensive Grado model PZE+(?) P-mount MM cartridge about 7 or 8 years ago which has seen very light use. It still sounds fine to my ears, but can the age alone degrade the sound? and to what degree? Thanks, jz
It depends upon the storage environment and suspension composition. High ozone like in L.A. attacks rubber fast. I live on an island off MA and the air is clean. We have salt air which attacks other things like metal. I have a lot of vintage cartridges and they are as good as new-30 years later!
Hi Nightdoggy - Glad to hear it.. It's been stored indoors away from direct sunlight, etc. and I live in the S.F. Bay Area so it's low humidity, etc. My '92 Toyota Tercel still looks almost new so I guess this is a good area to live for having things staying nice longer. The "o-ring" material where the cantilever meets the cartridge still seems to be compliant so I guess I'm good to go for awhile longer yet.. thanks for the feedback! jz
For a well set stylus, it's usually 2-3000 hrs of playing.
The rest is due to external conditions as mentioned above.
BTW cartridge manufacturers do specify a life span.
I emailed Grado this exact question and they replied there was no need to change cartridges because of this. They said you hear a loss of hi frequencies when you need to change cartridges.