How long is Facebook caching the sharing thumbnails?

Question

How long is Facebook caching the sharing thumbnails? I\'ve added a custom thumbnail for my page using:

Answer 1

Check the page with Facebook URL Linter, it seems to reload the thumbnails images in the cache.

http://developers.facebook.com/tools/lint

Answer 2

FYI the FB linter link above doesn't work anymore. This seems to do the trick though:

https://developers.facebook.com/tools/debug

Answer 3

Facebook images are cached on a different servers on a different location. According to what I have read, it will take 3 to 5 years before the image is refresh/deleted permanently after the last time it was accessed. So if the image keeps being accessed it won't be flushed. Not until you give up on shutting down your site.