There was a filter expert that used to post on IRV2. He worked for Cat and Cummins for years. Now retired. He wasn't an engineer but knew more than the engineers. He stated that filters do have a shelf life. BTW : also stated that you should never undo the hoses to your air filter on a DP to see if the filter is dirty. This exposes a lot of dirt to the clean side of the filter. I used to use Filter barn but lately they do not have a full selection of Fleetguard. Some of the FG prices were no better than Amazon. What a shame. I think there sources for overstock filters has dried up.
Moisheh
