This product is typically used for larger boilers in producing steam since the BTU content is high. The most important consideration (not the only consideration) when grading this fuel is the sulfur content, which can mostly be affected by the source feedstock.For shipment purposes, this product is considered a ”dirty oil”product, and because viscosity drastically affect whether it is able to be pumped, shipping has unique requirements. Mazut is much like Number 6 Oil, and is part of the products left over after gasoline and lighter components are evaporated from the crude oil.