K&N sealing
I had this exact same problem in Mom's pickup, as I had thrown my K&N away when I moved back to the swamp. I tried silicone sealant on the sealing surfaces, after their filter grease still let stuff "around" the filter, then let it set for a day before she drove it anywhere. 2K later, there was a fine layer of dust inside the intake tube. Hold it up to the light and I could see daylight through it. Got a new filter direct from K&N, same result- still see pinholes of daylight. I dont think dirt got around the sealant; it had to go through the filter. But, when I was in Colo, I had K&N in my CTD Ram, and a 6. 9 NA Ford, and the intake hose was always clean, even without the sealing grease. If you live in an agricultural area, or the local dust is super fine, the K&N will not perform, period. If the dust is sandier and not so small a particle, or if the engine is NA, you should do ok.
No more reuseable filters for me. Paper only for me. I realize the small amount of dirt in the engine will turn a million mile engine into a 750K engine, but still... ... I might look into a ProGard 7 once I get back out west.
Daniel