Oven racks are exposed to liquids and high heats. The combination of the two can rapidly age the metal rack. Corrosion and rust easily degrade the stability of the rack. Preventing rust is a matter of keeping the rack clean. However, once rust appears, you have a few options to repair or replace the rack.
Clean the Rack
A rusty rack does not have to be replaced or repaired. Cleaning it with an abrasive cleanser will help prolong the usefulness of the rack. Remove the rack from the oven, and set it on a flat surface. Sprinkle or spray an abrasive cleanser, such as one used for tubs and toilets, onto the surface. Scrub the metal with steel wool to remove excessive rust and grime. Rinse it thoroughly with water. Once a rack develops rust, it will continue to do so. Clean the rack weekly to help avoid damage from the rust.
Paint the Rack
High temperature grill paints help to protect a grill from rust and corrosion. An oven rack is exposed to the same elements as grills, so the rack will benefit from a good coat of paint. Clean the rack thoroughly with an abrasive chemical, and sand the whole surface with 120-grit sandpaper. Spray the rack with a high-temperature paint. One good coat for both the top and bottom of the rack will be sufficient to protect the rack from further damage.
Replace the Rack
Purchasing an oven rack does not require purchasing a new oven. The manufacturer for the oven will sell parts and accessories, including replacement racks custom built to fit the oven. After-market producers make racks that will fit the oven, although the replacements may be differently shaped. The aftermarket options are fully functional. You will have options for stainless steel, painted or speciality racks when purchasing a replacement. Removing and installing a rack just requires pulling out the old and sliding in the new.
Whether you painted the rack, replaced it or simply choose to clean the rack frequently, you can take a few steps to limit the growth of rust on the rack. Keeping the interior of the oven clean limits the moisture in the air to whatever happens to be cooking. Keeping the rack clean at all times removes build-up of grime and grease, which also promotes the growth of rust. Pull the rack out, and set the pans onto the rack, rather than sliding the pans onto the rack. Sliding causes minor scratches that build up in time, exposing the underlying metal. The tips do not prevent rust but will limit the impact or frequency of it.