- Monday Amata
- DOI: 10.5281/zenodo.17914662
- GAS Journal of Engineering and Technology (GASJET)
The performance and durability of internal combustion engines in tropical climates are significantly influenced by lubricant behavior under high ambient temperatures. This study investigates the comparative tribological and physicochemical performance of synthetic and mineral-based engine oils operated under Nigerian tropical conditions. Five samples three fully synthetic (including Energy Direct 5W-30, Mobil 1 5W-30, and Castrol EDGE 5W-30) and two mineral-based oils (Total Quartz 20W-50 and Mobil Super 20W-50) were evaluated through a 250-hour controlled engine test. Key parameters analyzed include kinematic viscosity at 40°C and 100°C (ASTM D445), viscosity index (ASTM D2270), oxidation stability (ASTM D943), total base number (ASTM D2896), and wear metal concentration (ASTM D5185). Results revealed that synthetic oils maintained stable viscosity with less than 6% variation after the test, whereas mineral oils showed up to 20% viscosity loss. Oxidation stability was significantly higher in synthetic oils (lifetime > 1,000 hours) compared to mineral counterparts (480 hours). Wear metal analysis indicated a 40–55% reduction in Fe and Cu content for synthetic lubricants, underscoring superior film strength and additive retention. These findings confirm that synthetic oils outperform mineral oils in mitigating oxidation and wear degradation under tropical heat stress, offering extended drain intervals and engine protection. The study recommends greater adoption of synthetic lubricants for vehicles and power systems in equatorial environments.
