Search Results

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 environmental performance of automobiles and automobile engines in particular is the foremost issue in the automotive industry today. In addition, engine durability performance is an essential aspect of engine oil performance. Four-cycle motorcycle engine oils formulated with dialkyl phosphate, a sulfur-free additive developed as an alternative to ZDDP, provide excellent environmental and durability performance in terms of longer drain intervals, cleanliness and low corrosion properties.

With environmental issues at the forefront of the automotive industries, there is a clear need to improve the fuel economy and longer drain performance of four-cycle motorcycle engine oils. Evaluation of oil consumption in actual engines was used to clarify an optimal volatility for engine oils, and the feasibility of using zinc dialkyl phosphate, a sulfur-free additive, as an alternative to ZDTP for improved of fuel economy performance was studied. Engine oils with optimized additives demonstrated excellent friction characteristics and wet clutch performance.

The authors have spent considerable time studying the sulfur-free additive ZP as a means to improve the environmental properties of engine oils. ZP is an alternative compound to ZDDP, which has been a key engine oil additive for over 50 years. The ZP molecule contains oxygen in place of the sulfur found in ZDDP. In our past studies, various engine tests confirmed that ZP-blend engine oils outperform ZDDP-blend oils in terms of long-life and fuel-saving properties. Moreover, by using ZP, levels of sulfur can be reduced without sacrificing the oils' primary performance characteristics, so there less of an adverse effect on emission control systems, and lower levels of vehicle emissions can be achieved. We conducted field tests involving dozens of vehicles to verify the fuel economy retention and long-life performance of ZP oils. We report the results in this paper.

We closely studied the action mechanism and deterioration mechanism of ZDTP (zinc dialkyldithiophosphate), used as an essential additive in engine oils for over half a century, and determined that the sulfur in ZDTP was hampering efforts to improve oil life. With this in mind, we developed a completely new engine oil blended with ZP (zinc dialkylphosphate), in which oxygen replaces the sulfur in ZDTP, and conducted engine tests. The tests confirmed that the newly developed oil provides long service life that cannot be attained with conventional oil formulated with ZDTP.

Zinc dialkylphosphate (ZP), a sulfur free analogue of Zinc dialkyldithiophosphate (ZDTP) has been synthesized and tested for engine oil application. The sulfur free engine oil based on ZP showed excellent TBN retention and engine cleanliness in several engine tests which were operated at low and high temperatures. A prototype low phosphorus (0.05%) and low sulfated ash (0.5%) engine oil exhibited even better longer drain performance than a fully synthetic engine oil containing 0.1% P and 1.1% sulfated ash. Thus, zinc dialkylphosphate can be a promising candidate as a ZDTP substitute for future catalyst system compatible engine oil.