Pengaruh Variasi Kekentalan Oli dengan Penambahan Engine additive terhadap Temperatur Kerja Mesin, Perubahan Viskositas Oli, dan Konsumsi Bahan Bakar pada Motor Bensin 4 Langkah

This study analyzes the effect of oil viscosity variation with the addition of engine additive on engine working temperature, oil viscosity change, and fuel consumption of a 4-stroke gasoline engine driving a water pump. A quantitative experimental method was applied using SAE 10W-30, SAE 15W-40, and SAE 20W-40 oils combined with 18 mL of Lupromax engine additive. Engine temperature was measured using an infrared thermometer, while oil viscosity at 40°C and 100°C was tested using the Simple Falling Ball Viscometer method, under pump valve openings of 25%, 50%, and 100%. The results show that the additive had a relatively small and inconsistent effect on engine working temperature, but consistently reduced the dynamic viscosity of all oil variations by 6.58–15.06% and lowered fuel consumption across all variations. The combination of SAE 10W-30 oil with 18 mL of additive at a 100% valve opening produced the most efficient performance, with the lowest fuel consumption of 0.24 mL/s. Increasing the valve opening also reduced engine temperature and fuel consumption while significantly increasing pump water discharge. These findings provide practical insight for selecting suitable oil viscosity and additive use in small-capacity 4-stroke gasoline pump engines.