Degradation Factors of Semi-Synthetic Lubricant oil for Gasoline-CNG Engine

Abstract

Compressed natural gas (CNG) as alternative energy has gained attention in public transport. CNG is clean energy, high octane, and less expensive than other fuels and can be operated in a dual-fuel engine system. This research studied various factors that affect the degradation of semi-synthetic engine lubricants for the gasoline-CNG engine. Samples were collected by distance lubricant oil analysis was conducted based on various ASTM methods. The kinematic viscosity (KV) analysis is an important property of Lubricant oil. It was measured at the structures of 40 and 100 °C. At 100 °C, the KV decreased from the heating phase, causing the intramolecular bonds to break, making the oil film thinner and leading to a catalytic oxidation reaction. The Fourier transform infrared (FTIR) spectroscopy showed that the lubricants undergo chemical changes in their properties due to increasing the carbonyl functional (C=O) concentration by oxidation product. The result indicated increased acid content and KV. It affects the corrosion of the internal engine parts. The total base number analysis indicates the cleaning agent performance of the lubricant. It was found that at a distance of over 15,000 km, the concentration of alkaline additive reduces half the amount of additive. This demonstrated that additives have been degraded from contaminations, such as dirt, water, metal, and soot.