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It is widely known that pellet-typed catalysts are deactivated by phosphorus (ZnDTP) that comes from engine oils. In this paper, the poisoning of monolithic three-way catalysts and oxygen sensors by engine oils is studied. First, catalysts and oxygen sensors were poisoned on the engine bench by test oils in which the quantity of phosphorus and ash was varied. Next, performance of the catalysts and sensors alone was examined and the vehicle exhaust emission at FTP mode was measured on a chassis dynamometer. The results indicate that phosphorus in engine oils poisons the monolithic catalyst and the oxygen sensor resulting in deterioration of the vehicle NOx exhaust emission. However, Ca sulfonate and Mg sulfonate detergents act by restraining phosphorus poisoning of the catalyst and the oxygen sensor. Through analysis of the catalyst and sensor surfaces, it is concluded that phosphorus poisons the catalyst and sensor forming a dense coating.

This paper describes lubricant technology which helps to prevent intake valve deposit (IVD) formation for use with conventional gasolines without detergents, as well as the IVD evaluation method used in testing. The FED 3462 method was modified to establish a new panel coking test method, with excellent correlation with the engine stand IVD test, for the quantitative evaluation of IVD. Tests have shown that IVD increases when the volatility of base oils becomes higher due to condensation and polymerization of engine oil additives. Furthermore, viscosity index improvers, metallic detergents and ashless dispersants have considerable effect on IVD formation. Based on various experiments, the authors have established a formulation technology for engine oils to lower IVD, which they incorporated in two newly formulated SG oils with lower IVD than conventional 5W-30 SG oil.