A successful lesson I learned from a Churrasco (BBQ) in Brasil:

1. Cleaned grill heated.
2. Olive oil sprayed onto grill - somewhat heavy.
3. Grill then used ( Half day/all night ). Charcoal & wood fired, and not gas.
4. Grill continued hot when finished, to char leftover material.
5. Grill scraped with a long handled, brass-wire brush.
6. Grill recoated with Olive oil spray.

The BBQ meats cooked were only coated with coarse rock salt, and no sugar-sauce. There was some fresh pineapple, dusted with Canelle (Cinnamon) and lightly grilled as a simple but delicious dessert item. No residue left on the grill.