"After cleaning the grate, the question is: ""To oil, or not to oil.""
Oiling your grill grate helps prevent food from sticking when cooking. To do this, dip a wadded paper towel in a little oil and, using tongs, wipe the oil evenly over the grate. Be careful not to use too much oil, because that's a sure fire way to start a good flare-up—a little goes a long way here."
If you cooking something that's been oiled itself, skip this step, because it's somewhat redundant. If you're unsure, it's always best to oil 'er up.