Still can't clean grill grates - what am i doing wrong?

are you cleaning them cold? heat the grill for 15 minutes first and brush while it's hot, the gunk comes off way easier. a ball of foil in tongs works if you don't trust wire bristles. for caked-on stuff: grates in a heavy bin bag with a cup of household ammonia, sealed, left outside overnight. the fumes loosen it and it wipes off in the morning. never mix the ammonia with anything else. oil them lightly after if they're cast iron.