Porcelain grill grates hold heat well and are rust-resistant, but you want to keep them cleaned and cared for. Any chips or scrapes in the porcelain will expose the metal underneath and allow water to seep in, which can create rust. So when cooking with metal tools be careful not to scrape or nick the grates.
When cleaning porcelain grill grates, don’t use metal or wire brushes. Use a soft bristle or a nylon grill brush. Burn off any food leftover on the grates. Then let the grates cool and scrub them with the nylon cleaning brush.