And that's because shipping has very tight margins, and they want cheap fuel, so they use something called bunker fuel, which was described to me by someone in the tanker industry as the dregs of the refinery, or just one step up from asphalt.
Y eso se debe a que los barcos tienen márgenes muy estrechos y quieren combustible barato, por eso usan algo llamado fuelóleo que me describieron en el sector petrolero como la escoria de la refinería, solo un paso encima del asfalto.