Russian Mazut M100 is a fuel oil that is manufactured to GOST specifications, GOST 10585-75 (not active), GOST 10585-99 Oil fuel (GOST is the Russian system of standards, much like ASTM, for example). Mazut is almost exclusively manufactured in the Russian Federation, This kind of oil is graded as the heavy furnace oil. The product is produced from the remains of raw oil processing. This kind of mazut is produced only from the low sulphur raw oil. 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.

The main difference between the different types of Mazut-100 is the content of sulphur. The grades are represented by these sulfuric levels:

Very Low Sulphur is Mazut M100 with a Sulphur content of 0.5%

Low Sulphur is Mazut M100 with a Sulphur content of 0.5%

Normal Sulphur is a Mazut M100 with a Sulphur content of 1.0-2.0%

High Sulphur is a Mazut M100 with a Sulphur content of 2.0-3.5%

The amount of sulfur affects how clean the oil burns, and in turn the emissions it creates, as well as the amount of buildup that accumulates within the engines and furnaces that burns it. M100 prices are often determined by its point of origin and mode of production. Apart from shipping charges and regulations, product quality is considered to be more essential.

When petroleum is distilled, fuel oil is produced as a residue or distillate. Any fuel oil is a form of petroleum that is burned to produce energy or heat for running an engine. These are usually low-quality oils that are heated in a furnace or boiler and used in a number of industries. MAZUT is such fuel and is typically used in generating plants and factories. Of course, different plants have expected requirements and specifications of their fuel and this is why MAZUT M100/99 and GOST 10585-75 are produced according to industry ISO standards.