Fossil fuels are the dominant source of energy today with the problem of their supply depletion becoming a global issue. Since stable energy supplies are necessary in order to sustain the activities of mankind, conservation of petroleum fuel and finding an appropriate substitute are critical. Additionally, solutions to global environmental pollution problems are simultaneously needed, such as the Kyoto protocol for global warming.The aim of this study is to investigate whether the combustion state of bunker oil can be improved by the mixing of DME (dimethyl ether), which is considered as a possible alternative fuel. The kinematic viscosity of DME blended fuel, as well as the engine performance characteristics of single cylinder direct injection diesel engine, was measured experimentally. In the kinematic viscosity measurement, a pressure cell type viscosity measurement system was established in order to apply the volatile DME blended fuel. The nozzle opening pressure was changed in order to obtain different injection characteristics in the diesel engine.For diesel engine applications, DME has a problem of poor lubricity due to its lower viscosity and Bunker oil has the problems of exhaust emissions and high viscosity. Of special note, Bunker oil needs to be heated up over 100 degrees centigrade to reduce its viscosity applicable for marine diesel engine use. In the present study, Bunker oil can be used without heating in diesel engines by mixing with DME.