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The film-forming, friction, and antiwear properties of zinc dialkylphosphates (ZDPs) were investigated and compared with the corresponding zinc dialkyldithiophosphates (ZDDPs). The primary ZDPs generally show similar friction and antiwear performance to the primary ZDDPs, although some differences are seen between them in film-forming properties. For the secondary ZDP and ZDDP, there are some clear differences in their tribological properties. This indicates that the properties of the primary ZDPs and ZDDPs may be controlled predominantly by adsorbed films consisting the intact additives and/or their decomposition compounds, and that the properties of the secondary ones may be controlled by glassy reaction films consisting zinc/iron polyphosphates.

The authors evaluated the durability of current zeolite-type SCR (Selective Catalytic Reduction) catalyst system in terms of poisoning from engine oil components, such as phosphorus, sulfur, calcium and zinc. The engine oil types used included typical CF-4, a sulfur-free type and an ultra-high SAPS (Sulfated Ash, Phosphorus and Sulfur) type, etc. After 500 hours' engine operation with these oils, the NOx conversion rates were measured and compared. The test revealed no serious deactivation of the catalysts, but we observed some trends concerning the poisoning and its effects on the catalysts' activity. We also analyzed the contaminants on the catalysts and studied their effects.