Here in Ohio and shooting corrosive ammo you have to be pretty diligent with running water through them after use, especially AKs in certain areas. Humidity can suck it
I do like Fireclean on gas tubes, gas blocks and other internal parts that see gas and heat directly but not necessarily sunlight. I have taken apart my AR just to see what the VDI life coat looks like after some rounds and the gas tube slide right out of the gas block with no real effort and any ash wiped right off.