Abstract:
Presently, it is not clear in selecting engine lubricants for optimum uses and further test data are needed. This research work was to be studied performance of conventional, semisynthetic and fully-synthetic lubricants used in passenger cars. The main objective of the work was to compare performance in reducing friction power and wear resistance. In addition new lubricant type, modified mineral lubricant which is expected to be a popular product, was included in the study. The study was divided into 2 phases. The first phase was conducted in the laboratory. Measurement of engine friction at firing and motoring conditions using several lubricants was done. The second phase was the field test using 8 cars running for 10,000 kms. in the real condition. The purpose of the study was to evaluate engine wear for different lubricant types. Sampling of used oil for analysis was conducted from 5,000 - 10,000 kms.Results show that engine friction power was reduced using semi-synthetic, kllysynthetic and modified mineral lubricant comparing to convention one. It has evidence that viscosity is the main factor affecting friction power and synthetic lubricant usually sells wit11 lower kinematic viscosity. For the same viscosity grade synthetic lubricant slightly help reduce friction power comparing to conventional one. For the wear test, it shows that all kind of lubricants produced similar results for real operating condition in Thailand, It is found that increment of silicon is interesting parameter used to indicate for oil changing limit and it should be a topic of future research work.It can be concluded from friction power and wear tests that the conventional lubricant is suitable and good enough to use in passenger cars for normal operation in Thailand. The conventional lubricant was proved to be used up to 10,000 kms. without any problems.