Narrator: It makes the world go round, and up and down and side to side. In our relentless battle to keep moving grease, in all its forms, is the unsung hero. Without it the countless wheels of our lives would grind to a halt. From aircraft carriers to canals, grease of all kinds keeps everything rolling along smoothly and fast. You know what the squeaky wheel gets. It's the untold story of Grease, on Modern Marvels.