If your grates look like a abandoned shipwreck, it’s bath time. Remove the grates and place them in a big plastic bag or a shallow tub.
Pour white vinegar over them until they’re fully submerged. Let them soak overnight—yes, you have to wait. Rust is a slow loser.
In the morning, the vinegar will have loosened the rust like a bad relationship. Rinse the grates with water, then give them one more scrub with your wire brush. The rust should flake off like old paint.
How To Clean Rust Off Barbecue Grates at Beth Anker blog
