Ammo box half full of fuel oil, a little ATF, a little motor oil, a little WD-40, a little gun oil, whenever a can is coming up empty it gets dumped in the cleaning can. Pull the grips, dunk the gun, do what I was going to do and when I'm good and ready in an hour or a week I pull the gun and what the air hose doesn't get the brush will and then the air hose. Then I lube what needs to be lubed, grips back on and I'm good to go. Every couple of months I strain the mix and add more fuel oil if its getting low. No special formula and I don't have a rust problem on any of my handguns. Only thing I really do any work on is the bore, my rag has to come out of the bore white before I consider that gun clean.