A fuel oil “A” composition wherein the density (15C) is 0.8400 to 0.8900 g/cm3, the kinematic viscosity at 50 C is not less than 2.000 mm2/s and the cetane index (old) is not less than 35, and also wherein the sulphur content is not more than 0.100 mass %, the sulphur content of sulphur compounds having a boiling point at or above the boiling point of dibenzothiophene is not more than 110 mass ppm, and the residual carbon content of 10% residual oil is not less than 0.20 mass %.

A fuel oil A composition wherein the density (15C) is 0.8400 to 0.8900 g/cm3, the kinematic viscosity at 50 C is not less than 2.000 mm2/s and the cetane index (old) is not less than 35, and also wherein the sulphur content is not more than 0.100 mass %, the sulphur content of sulphur compounds having a boiling point at or above the boiling point of dibenzothiophene is not more than 110 mass ppm, and the residual carbon content of 10% residual oil is not less than 0.20 mass %.

Methods are provided for determining the compatibility of various grades of fuel oils, as well as methods for modifying fuel oils to improve compatibility and improved compatibility compositions. It has been discovered that the toluene equivalent solvation power of a blend of fuel oils does not vary in a straightforward manner with respect to the toluene equivalent solvation power of the individual blend components. Instead, it has been determined that the asphaltene content of the individual components can also influence the toluene equivalent solvation power of the final blend. Based on this discovery, methods are provided that can allow for modification of one or more components of a potential fuel oil blend. This can reduce and/or minimize the likelihood of asphaltene precipitation when a fuel oil blend is formed.

A synergistic mixture comprising from 1 to 99.9% by weight of compounds having structural elements (I) ##STR00001##
in which the free valencies on the oxygen atom and on the nitrogen atom may be combined to form a five-, six- or seven-membered ring and the benzene ring may also bear substituents at one or more of the free positions, and from 0.1 to 99% by weight of sulfur-containing organic compounds with antioxidant action. This synergistic mixture is suitable as a stabilizer for stabilizing inanimate organic material, especially mineral oil products and fuels, against the action of light, oxygen and heat.

Methods are provided for determining the compatibility of various grades of fuel oils, as well as methods for modifying fuel oils to improve compatibility and improved compatibility compositions. It has been discovered that the toluene equivalent solvation power of a blend of fuel oils does not vary in a straightforward manner with respect to the toluene equivalent solvation power of the individual blend components. Instead, it has been determined that the asphaltene content of the individual components can also influence the toluene equivalent solvation power of the final blend. Based on this discovery, methods are provided that can allow for modification of one or more components of a potential fuel oil blend. This can reduce and/or minimize the likelihood of asphaltene precipitation when a fuel oil blend is formed.

A synergistic mixture comprising from 1 to 99.9% by weight of compounds having structural elements (I) ##STR00001##
in which the free valencies on the oxygen atom and on the nitrogen atom may be combined to form a five-, six- or seven-membered ring and the benzene ring may also bear substituents at one or more of the free positions, and from 0.1 to 99% by weight of sulfur-containing organic compounds with antioxidant action. This synergistic mixture is suitable as a stabilizer for stabilizing inanimate organic material, especially mineral oil products and fuels, against the action of light, oxygen and heat.