Protect valuable tools and equipment with commercial-grade corrosion inhibitors from Grainger. A corrosion inhibitor deposits a moisture-displacing film on the surface of steel, cast iron, and other ferrous materials to help prevent rust and corrosion. Some types of corrosion inhibitor can be added to coolants, fuels, boiler water and other fluids to help protect interior metal and alloy surfaces. Turn to Grainger for corrosion inhibitors and all your rust-proofing needs, inside and out.