Voluminosities of EGR Engine Soot and Carbon Black: A Bench Test for Fresh Engine Oils

Abstract

To qualify for an API classification, an engine oil must pass the sequence tests for that category. Today, sequence tests for oil classifications are very costly. As a consequence, additive companies are seeking bench tests to reduce testing costs. Among the important criteria for engine oils are low wear and limited viscosity increase. Both wear and viscosity increase depend on the degree of agglomeration of soot suspended in the crankcase oil. Typically, dispersants are used in the engine oil to limit the agglomeration of soot. Voluminosity, the effective volume of the soot in the oil, is a quantitative measure of the degree of dispersion of the soot in the oil. It provides a means of characterizing soot in used oils and may provide a means of assessing candidate engine oils, using a soot surrogate. In this paper, data are presented on the voluminosities of engine soot and soot surrogate (a commercial carbon black). The voluminosity of carbon black differs from that of the engine soot. Nevertheless, the voluminosities of the carbon black in three fresh candidate engine oils were found to correlate with the Cummins M-11 exhaust gas recirculation (EGR) engine test wear results. Paradoxically, this correlation is exactly opposite to what is expected. *Deceased