How can I clean outside grill grates?

Turn the flame on "low" as soon as you remove the food from the grill.

Turn the grill to the "high" setting until the smoke stops to burn off any remaining food residue. Turn off the burners. Brush the grill grates clean with a brass wire grill brush. Spray the grill grates liberally with vegetable oil to loosen any food particles that may still be stuck on the grate.

put grates in a tub pour in hot coffee let set overnight

Soak in bathtub overnight with hot coffee..

Remove the grates and soak over night in a black plastic bag with Amonia

i clean the grill grates the same way I clean my oven grates.....spray with oven cleaner...stick in black plastic bag. Let sit overnight. Hose off next day.

I found burned on grease soaked off overnight with a mixture of baking soda and blue Dawn dish detergent. Just make a paste, spread evenly and let it sit for a few hours. If you have the space, you can also use this mixture and let the grills soak in the sink under water, too. BTW, this is the best I've found for cleaning my oven, too.

Several methods--use baking and water in spray bottle--spray down well and let sit several hours -wash off. Or oven cleaner.