I install bank equipment, ( Vault doors, Safe Deposit Boxes etc.) Most of the vault doors and S/D boxes are made from mild steel or wrapped with stainless steel. If you use WD-40 on stainless, after time it will give it a yellow tint. If you use stainless polish on mild steel it rusts, because of the water in the stainless polish. DON'T TELL ANYONE, I do use WD-40 on stainless just before we turn the equipment over to the bank, because it does give it the best shine possible. I never tell anyone from the bank to use WD-40 on their vault door or S/D boxes. Always use stainless polish. When we go back and do maintance on the door, I sneak a quick wipe with WD-40 so it will look new again. WD-40 is great on stainless once in while. but not as a everyday polish, unless you like a yellow tint.
