Abstract: A new type of fuel oil with low cost and low viscosity made of heavy oil or residue oil. The fuel oil is low cost, low viscosity and low pollution and includes base oil formed by adding waste plastic disposal oil made through thermal decomposition to heavy oil or residue oil of high viscosity, thereby decreasing the viscosity. The base oil is then provided with water and emulsifier to form water-in-oil emulsion fuel oil. The emulsifier is formed by mixing caustic soda (NaOH) and the calcium chloride (CaCl2) and water. Substantial reduction in generation of pollutants in the exhaust gas is achieved when the fuel oil used in a combustion engine. The fuel oil is especially suitable for large and high power vessel engines.