Alcohol will be an exceptional alternative fuel for existing diesel engines because of its built-in fuel-improving properties (high cetane number and high energy content). Biosynthesis of N-heptanol by means of engineered microbes, such as the Clostridium species and Escherichia coli, is an active area of research. Hence, extensive investigation on the compatibility of N-heptanol in existing diesel engines is necessary. This study examined the effect of heptanol mustard oil biodiesel blends of varying proportions on the emission and performance patterns in a 1,800 r/min constant-speed immobile diesel engine. The main objective of this investigation was to investigate the reduction in all the emissions and increase the performance characteristics associated with neat mustard oil biodiesel when deploying three different fuels. Base catalyzed transesterification process was employed to convert the mustard oil into mustard oil biodiesel. Heptanol with 98.4 % purity was used as an oxygenated additive. The experimental results revealed that converting heptanol to mustard oil biodiesel caused a significant reduction in hydrocarbons, carbon monoxide, nitrogen oxides, and smoke emissions when compared to mustard oil biodiesel in naturally aspirated conditions.