I first used it on a box of drill bits found in a yard. Been laying out at least a year. Lay them in a glass cake pan, poured on the vinegar, then covered it up and took it outside. I really hate the smell of vinegar. In 3 days I checked, and they all have a heavy layer of black crud, but no rust. Washed them, dried, then wiped down with oil. Some of them came out shiny again. Not nearly as amazing as those pipe wrenches, but it works for me.