See the video.

來源: 於 2011-07-17 18:47:20 [舊帖] [給我悄悄話] 本文已被閱讀：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.