This study investigated the potential of biofuels as sustainable alternatives to petroleum based source in CI engines, through focus about biodiesel derived from Terminalia catappa seed oil. Specifically, it scrutinized the consequence of incorporating aluminum oxide into biodiesel plus implementing Lanthanum Zirconate thermal layers to engine elements. Four source variations were inspected: diesel, Terminalia catappa seed oil, 80% diesel and 20% Terminalia catappa seed oil, and a blend of 80% diesel, 20% Terminalia catappa seed oil, and aluminum oxide nanoparticles. Key fuel characteristics, including density, calorific value, viscosity, Cetane number, and flash point, were measured. The engine's performance was assessed through parameters such as brake specific fuel consumption, brake thermal efficiency, emissions, heat release rate, and peak cylinder pressure. Findings revealed that the 80% diesel, 20% Terminalia catappa seed oil, and aluminum oxide nanoparticles blend, when used in a coated engine, demonstrated a 10% drop in BSFC and a 6.4% augment in BTE relative to pure diesel. Emissions were also significantly reduced: CO emissions decreased to 0.051 vol%, HC to 31 ppm, and smoke opacity to 45%, representing reductions of 43%, 13.8%, and 10%, respectively, compared to diesel. These consequences underscore prospective of biodiesel combined with additives in addition to thermal layer to augment performance plus reduce emissions in diesel engines.