from long term users thats all. As for stock mounts - they are considers a wear item, no one expects them to last forever. While I have never seen them fail at 20K (but how old?) I do expect to replace them any time I have a engine out of a car - which means they are 10+ years old or so when I see them. To me 10+ years on a stock rubber piece isn't a bad return on $160 or whatever they cost to replace.