500 hp crate engineFeb 13, 2013 · After you prep the undercarriage (wire wheel, brush, flapper, whatever you prefer). Treat the metal with a mix of 3 to 1 water and vinegar. Scrub the carriage with a 3m pad and the mix. Let it sit for an hour and come back and wash it down (use a hose and a fresh 3m pad). Then dry it, use an air hose if you got one. Steel lugged bike frameRust Check Coat & Protect provides the required protection for exposed areas of your vehicle’s undercarriage. Coat & Protect is formulated as a premium undercarriage treatment that forms adherent and wash resistant, but non-drying and self-healing protective films that will not crack or peel.