I've tried may cleaning formulas and different oils & lubes over the years. Since I used Rem Oil a few years ago, it's all I use for coating the bore for rust prevention now. I clean the bore, run some WD-40 through to remove any lingering moisture, run a dry patch or two, then a patch soaked with Rem Oil. Not a speck of rust that way - and I've stored them for several months that way with no problems.