What happens if you accidentally leave racks in a self-cleaning oven?

Leaving chrome or stainless steel oven racks inside the cavity during a high-heat self-cleaning cycle—which reaches temperatures exceeding 800 degrees Fahrenheit—causes permanent physical and chemical damage to the racks. The extreme thermal stress destroys the shiny nickel or chrome electroplated coating, causing the metal to warp, discolor into a dull gray or chalky white finish, and lose its protective barrier. Furthermore, the heat strips away the specialized graphite lubrication on the rack glide rails, making them sticky and difficult to slide. You can troubleshoot rack damage easily by inspecting the finish. You can verify that your racks are ruined when you notice a warped structure and rough texture; you can restore minor stiffness by rubbing vegetable oil onto the cooled rails.