I gotta say.....
These military guys are idiots.

They're using up precious fuel setting zombies on fire???  Anything that would be sufficient to cook a zombie would be more of a threat to the ones wielding it. Either you get a zed shambling towards you that's on fire, or you start a raging fire that incinerates thousands of square miles before it stops, because hey folks, there's no forest rangers to put it out no more.