Preheated Schizochytrium sp. raw MAO was evaluated as a fuel in a single-cylinder four-stroke diesel engine to produce a comparative study of MAO and DO critical parameters. In particular, brake power, brake specific fuel consumption, brake thermal efficiency, in-cylinder pressure, exhaust gas temperature, NO_x and CO emission were investigated. Additionally, an engine durability test for longevity was undertaken over a 30 h period, using raw MAO as the fuel. The study demonstrated that the preheated MAO could be successfully used in a Diesel engine smoothly. The use of MAO reduced the engine brake power by 26% and increased brake specific fuel consumption by 20%. The most significant finding from this research study is that there was a significant reduction in NO_x and CO emission by 42% and 60% when using raw MAO, respectively. Therefore, these findings demonstrate that algae oil is a highly credible fuel for use in diesel engines and offers a promising solution to diesel engine emissions.