Oil hot cast iron after every cook.

Scrub the grates while they’re still hot, then wipe them down with a thin layer of oil.

Rust on cast iron is just moisture + oxygen + time. The best way to fight it is to never let water sit on the metal. That means: clean the grill when it’s still warm (not screaming hot, but hot enough that water sizzles off instantly). Use a wire brush or a ball of crumpled foil to scrape off food residue. No soap. No soaking. Then take a paper towel with a high-smoke-point oil (canola, vegetable, grapeseed) and rub it over the grates until they look glossy but not dripping.

If you let the grill cool completely before cleaning, that’s when gunk sticks and moisture gets trapped. And if you skip the oil, the bare iron will flash-rust overnight, especially in humid weather. A lot of people overthink this—special cleaners, vinegar baths, seasoning cycles. None of that is necessary. The single trick is: clean hot, oil immediately.

Your grates will last through a hundred summers.