I don't use soap, soak it in a bucket, then using a water hose, just turned a trickle, hold the filter sideways and allow the water to flow from the inside out, rinsing the dirt out until clear. Pressure spraying is a good way to rearrange the fibers, possibly making holes, especially when full of water, so I allow it to air dry.
In my experience they have a huge dirt capacity, take a very long time to get dirty enough to show significant restriction. In the past, I cleaned it every year before Cruise Moab. A couple of years ago installed a filter minder. Ran that filter for a couple of years, ~24K miles, in lots of caravan type desert runs where you can hardly see the rig you are following and the filter minder reading never changed.
That filter is old, has a ton of trail miles, has been cleaned several times. Wanted to see if a new one would show any difference, so installed one before CM this year, it reads exactly the same. The plan is to run this one until it shows significant restriction, I expect that to be a very long time.
The conclusion is that I was washing it way too often. The huge surface area combined with the cyclonic/tuna can design is very efficient. I would guess that a rig that lives in a more humid area, doesn't travel in dust clouds, would easily go 50k miles before needing to be cleaned and that is likely conservative. I will be just cleaning the tuna can and watching the gauge until restriction is noted, then will report, don't hold your breath!
