Remove as much stuck-on matter as possible from the grill grate by scrubbing it with a grill brush.
Spray the grill grate with natural, fume-free oven and grill cleaner. Allow the grill cleaner to soak for the time indicated in the grill cleaner directions then wipe down the grill grate with a damp sponge or cloth.
Clean any spills or loose matter from inside the oven before beginning the self-cleaning process.
Open windows and doors in the home to allow for smoke ventilation during the cleaning process.
Place the grill grate on an oven rack and set the oven to self-cleaning mode. Run self-cleaning for at least two hours.
Allow the oven to cool for two hours. Remove the grill grate and wipe it down with a damp sponge or cloth. Remove any ash from the oven floor and wipe down the oven walls.
Season the grill grate. Rub steel grates with cooking oil. Rub cast iron grates with shortening.