Permatex Heavy Duty Radiator Cleaner removes rust and scale from automotive engines, radiators and water jackets. It also cleans and unclogs steam cleaner coils and boiler tubes. Not for use in aluminum radiators. Permatex does the job when it comes to specialty cleaners to dissolve rust, clean plastic or remove gum and deposits from parts. Permatex offers a complete line of professional strength cleaners and degreasers, each formulated to the highest standards and quality.