Selecting lubricating oil for two-stroke gasoline engines: a multi-criteria decision-making approach

Abstract

The two-stroke engine boasts advantages in terms of simpler manufacturing and a smaller size when compared to the four-stroke engine. Vehicles powered by two-stroke engines can thus effortlessly overcome road obstacles compared to their four-stroke counterparts. However, the use of a two-stroke engine results in higher carbon monoxide and hydrocarbon emissions than that of a four-stroke engine. This discrepancy places greater demands on the selection of lubricating oil for two-stroke engines compared to four-stroke engines. In market, there exists a multitude of lubricating oil options tailored for two-stroke engines, each characterized by varying technical parameters. These disparities are expressed through factors such as density, viscosity index, viscosity, and combustion temperature, among others. Consequently, the task of choosing the optimal lubricant becomes a complex endeavor for consumers. In this study, an examination of lubricant selection is presented using a Multi-Criteria Decision-Making (MCDM) approach. The MCDM method employed in this article is the Combined Compromise Solution (COCOSO) method. The selection of the best lubricant is based on an evaluation of four distinct types. Each type of oil is described by four key parameters (criteria): density, viscosity index, viscosity at 100 °C, and viscosity at 40 °C. The weights for these four criteria are determined through three different methods, including the Entropy method, Criteria Importance Through Intercriteria Correlation (CRITIC) method, and Standard Deviation (SD) method. Thus, the ranking of lubricants is conducted three times, corresponding to these three weighting methods. The results indicate that the best oil choice remains consistent regardless of the weighting method applied