I was curious ... If you almost always use recirculation, would you have to change out the filter at far greater intervals? I almost never use the outside air, whenever it automatically switches, I switch it back (or as soon as I notice). I prefer my stale air opposed to any of the poor outside smells that can still leak past the filter (sewage treatment plants, really horrible car/semi exhausts, landfills, poor animals that didn't make it).

I definately like saving more money by not replacing something that isn't bad.