tool storage

Hi All, I have a basement shop, while it's not overly damp rust forms on bare steel if left unprotected. I recently went through deep cleaning and reorganization and found a lot of tools, particularly taps, dies, files and such had rusted. I sprayed most of these items with WD-40 before storage...

My shop is dry, no humidity. I have storage for my tools. But I continue to deal with staining/corrosion on instruments over time. In the past, I've used whatever was on hand but nothing with detergents. Right now it has been light machine oil. It works o.k. for some tools, but not so good for...