When I brought my coach at 19,000 miles I told the dealer to replace all the filters. When I had a breakdown with the jacks I had to open the side a/c condenser and swing it out for access to the hydraulic pump. Also in there I found two filters that weren't changed as in still original from the factory.
I had since in the 14 months I owned this coach put an additional 19,000 miles on it. Can you imagine my horror knowing there is 38,000 miles on the primary fuel/water separator and the air brakes/air bag suspension air dryer?
Needless to say I changed both filters today, got them cheaper through O'Reilly's and order the replacement dryer filter. Lesson learned, never trust a dealer to watch your back. I'm am lucky that these filters didn't give me any trouble.