A Comparative and Analytical Study of the Energy Economy and Environmental Impacts of Engine Oils in Nigeria: An Examination of Thermophysical Properties

This study investigates the energy economy and environmental impacts of commonly-used engine oils in Nigeria by analyzing their thermophysical properties. Limited public literature on these oils has left several energy and environmental issues inadequately addressed by governmental regulators. Ten popular engine oils were selected: Master Super (SAE 40), Abro (SAE 20W-50), Sea Horse (SAE 20W-50), Oando Oleum Super (SAE 40), Climax Auto Lube (SAE 40), Conoil Golden Super (SAE 40), Total Classic (SAE 40), Tonimas ENEZ Heavy Duty (SAE 40), Mobil Super (20W-50 XUP), and Ammasco Vital 2000 SL (SAE 20W-50), coded as S1 through S10, respectively. Thermophysical testing revealed that dynamic viscosity decreased across all samples as temperatures rose from 40°C to 100°C, with S10 showing the highest viscosities (427 cP and 106 cP) and S1 the lowest (255 cP and 66 cP). The oils also showed variations in density (882.7–895.0 kg/m³), thermal conductivity (0.1430–0.1463 W/mK), specific heat capacity (1832–1921 J/kgK), and thermal diffusivity (8.433–8.923 × 10⁻⁹ m²/s), indicating discernible property relationships. Flash points ranged from 230°C to 262°C. Samples S2, S3, S4, S8, S9, and S10 demonstrated high wear protection under stressful conditions but tended to degrade more rapidly at elevated temperatures. In contrast, S1, S5, S6, and S7 exhibited balanced properties, optimizing engine performance, reducing fuel and energy consumption, and potentially minimizing toxic emissions. The findings underscore the need for further regulatory focus on engine oil standards to support energy efficiency and environmental protection.