i replaced mine shortly after i bought it, the whine got real annoying real quick. i also replaced the belt as well.

 

While its amazing that some folks have over 100K (and 200K) on their belt and idler pulley, I change the idler pulley whenever I do the belt, at every 45 to 50K. I prefer to not have a 20 dollar belt leave me stranded on the roadside, so I do it at these intervals as a preventative maintenance.

 

131,XXX and still original.