The problem with oils is that they become congealed over time and build up a sticky sludge. I use cat litter made of silica, put some in a coffee filter or some such. Heat in a 240º oven for 4 hours and place in every box (or drawer in my case). During our Coastal Oregon winters I may re-heat them once a month or so with no other protection and have excellent corrosion protection without messy oil left over 'goop'. Also use same for my powder and primer bunkers to maintain 50% humidity during rainy periods.