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Soot-related oil thickening problems have been reported over the years by multiple OEMs in Europe, Japan, and in the U.S.A (1,2,3). The earliest problems, from the late 1970s, were often attributed to adverse changes in operation [lower engine speeds, heavy loads and low air/fuel ratio, or severe operation such as stop-and-go service (3)] which led to a high soot generation rate. In the late 1980s, the emission legislation became more stringent and soot-related oil thickening concerns resurfaced. It appeared that even engines that produced a relatively low level of soot in the exhaust gas showed a high level of soot contamination in the lubricant (4). For the oil and oil additive industry, the Mack T-7 engine test offered a useful tool to evaluate the ability of oils to disperse soot, but it has been noted that the industry remains without a test based on a European engine to adequately evaluate an oil's ability to disperse diesel engine soot.