| 摘要 |
PROBLEM TO BE SOLVED: To provide lubrication of four-stroke marine diesel internal combustion engines, referred to as trunk piston engines, which diminishes the loss of BN of a lubricating oil composition and diminishes the increase in viscosity during use thereof.SOLUTION: In the use of a nitrogen-containing ashless dispersant additive in an amount providing N in the range of 50-150 ppm, preferably 75-125 ppm, by mass, in a trunk piston marine lubricating oil composition for a medium-speed compression-ignited marine engine, fueled by a heavy fuel oil, and lubrication of the trunk piston by the composition, the composition has a BN in the range of 20-60, preferably 30-55, the use being to diminish the loss of BN and to diminish the increase in viscosity without adversely affecting deposits performance.SELECTED DRAWING: None |
