Operational performance of eco-friendly engine oils formulated with the sulfur-free additive ZP 2007-01-1991
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. For the field tests, we used ZP oils of 10W-30 and 5W-30 viscosities, and commercial vehicles operating in different parts of Japan.
The results showed that the ZP oils provided long-life performance superior to that of the ZDDP oils. Furthermore, the ZP oils maintained their friction-reducing performance after long-distance driving, with excellent fuel economy retention. Furthermore, there was no excessive increase in the concentration of metallic elements in the oils, indicating that the ZP oils provided good anti-wear protection, and would not cause problems of reduced engine reliability.