Mazut is a type or grade of fuel oil that is typically produced in Russia and its neighboring countries. The Mazut Fuel Oil is heavy but low quality fuel oil that is used in generating plants and similar other applications. The other large usage of Mazut Fuel Oil is in larger boilers for producing steam as it has high BTU content. The Mazut Fuel Oil is considered as a dirty oil product and while grading it the sulfur content is taken into consideration so as to determine it as low, very low, high or normal sulfur Mazut.