Influence of Alkalinity of Marine Diesel Lubricants on Engine Performance

Abstract

One of the major concerns regarding lubricants for medium speed diesel engine is how alkalinity of lubricant influences on lubrication performance under high sulfur fuel operation.
In the present study, the tests were conducted using Mitsui 1L42X test engine together with other laboratory instruments to investigate the influence of TBN of lubricant on thermal stability, piston ring wear, detergency, and physical properties of used oils.
The engine test results suggest the presence of suitable TBN which minimizes the piston ring wear. Higher TBN oils give less piston deposit and less insoluble product in used oils. The thermal stability in differential thermal analysis is improved with increasing of TBN while panel coker test result shows minimum deposit formation at medium TBN.
These results are considered to be caused by the action of high alkaline detergent additive in the lubricants and the combustion products including acidic products from high sulfur fuel.