See the video.

来源: 于 2011-07-17 18:47:20 [旧帖] [给我悄悄话] 本文已被阅读：次

http://www.youtube.com/watch?v=VaRdFMgJj9Y

I believe it's recommended to replace the filter every 30k miles.  Certainly it also depends on the driving conditions.