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Lubricant field problems due to diesel engine soot have been reported in stop-go vehicles in Europe and the U.S. Soot generated in these vehicles can cause heavy-sludge, high lubricant viscosity increase, or oil gelling. In field and dynamometer testing, the authors demonstrate that certain oil formulations minimize these problems. Oils labeled CD/SF/EO-K produce significantly different soot dispersancy and viscosity control. In addition, formulations which provide adequate soot dispersancy also reduce engine wear.

At today's low oil consumption rates, high speed diesel engines with chromium-faced rings have experienced corrosive wear problems. This report defines the alkalinity required to prevent these wear problems; and the appropriate oil drain interval. In addition, the mechanisms of chromium-faced ring wear are identified. The study is based on three different engine types—direct injection two-cycle (DDA 8V-71TA), direct injection fourcycle (Mack ETAZ 673), and precombustton chamber fourcycle (Caterpillar 1Y73).

The purpose of this paper is to define the factors which affect oil consumption and cylinder bore polishing. The investigation focused on top land deposits, fuel sulfur, and lubricant viscosity in a series of direct-injection diesel engine tests in the U.S. and Europe. In these engine tests it was demonstrated that excessive top land deposits cause high oil consumption and cylinder bore polishing. Cylinder bore polishing can also be caused by corrosion when high sulfur fuels are used with oils of low alkalinity values. Maintenance of the Crosshatch honing pattern is critical to oil control, low ring wear, and prevention of ring scuffing. Low oil consumption and low cylinder bore polishing can be achieved with lubricant formulations which minimize the top land deposit and provide sufficient alkalinity to minimize the corrosive aspect of bore polishing.