Physical properties of small engine lubrication oils after 3000 km mileage run

Periodic change of engine lubrication oil is essential to maintain the health and longevity of an engine. The most common practice for motorcycles is to have an oil change at every 3000km interval. This study was done to analyze different base of engine oils between different engine oil brands by comparing its physical properties, namely density and viscosity. Three grades of commercially available lubricant oil for small motorcycle engines were tested: mineral (15W-40), semi-synthetic (10W-40) and fully-synthetic (5W-40). The oils were tested according to ASTM D 445 and D 1298, in its fresh state straight from the bottle, and after 3000 km mileage run in twelve 150cc 4-stroke single cylinder motorcycle engines. The test results showed that the density of engine oil samples increased while the kinematics viscosity decreased after the 3000 km mileage run. Different level of changes were recorded for different lubrication oil grades. Six out of twelve oil samples were found to have viscosity values (measured at 100oC) lower than the SAE J300 specification after the 3000 km mileage.