High Temperature Liquid Lubricant for Use in Low-Heat-Rejection Diesel Engines

Significant progress has been made in the development of high temperature liquid lubricant candidates for low-heat-rejection diesel engines. Program objectives were the reduction of lubricant-derived deposits and the optimization of lubricant thermal/oxidation stability. Lubricants with established performance in high temperature multi-cylinder LHR engines were used to develop and calibrate bench tests for optimizing lubricant deposition characteristics and stability. Base stocks with optimum combinations of low deposits and high stability were selected with these bench tests. These base stocks were used in the additive selection phase of the program. Existing LHR Engine test data exemplify the need for ashless lubricants to avoid metal related deposits in the upper cylinder area. Candidates with 60% less sulfated ash than typical commercial lubricants have been formulated for single-cylinder engine tests. These candidates exhibit lower deposits and higher stability in bench tests than the lubricant with the best performance to date in multi-cylinder LHR engine tests.