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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.

In recent years, problems such as global warming, the depletion of natural resources, and air pollution caused by emissions are emerging on a global scale. These problems call for efforts directed toward the development of fuel-efficient engines and exhaust gas reduction measures. As a solution to these issues, performance improvements should be achieved on the oil that lubricates the sliding sections of engines. This report points to features required of future engine oil-such as contribution to fuel consumption, minimized adverse effects on the exhaust gas aftertreatment system, and improved reliability achieved by sludge reduction-and discusses the significance of these features. For engine oil to contribution of engine oil to lower fuel consumption, we examined the effects of reduced oil viscosity on friction using gasoline and diesel engines.

The limits and issues of reducing the viscosity of ATF were studied. The threshold for viscosity reduction at high temperature after shearing was determined through the data from field tests. Base oils and viscosity index improvers were selected to reduce the viscosity at normal temperature as low as possible, maintain the viscosity at high temperature after shearing. This experimental ATF was evaluated on several properties. However, this ATF had problems with the durability of friction materials and bearing fatigue life. Therefore, base oil's viscosity and the type of base oils were optimized to improve these problems. The developed low viscosity ATF showed same performance as conventional viscosity ATFs.

It has long been sought to improve the low-friction properties and low-temperature viscometric characteristics of mineral oil based automotive manual transmission fluid(MTF), automatic transmission fluid(ATF), and power steering fluid(PSF). Because, however, It has been impossible to make such improvements on the mineral oil base,synthetic oils such as poly- α -olefin have been substituted to achieve the required improvements in the lubricants. But the synthetic oils have a drawback:high cost. Thus a new series of mineral oil based lubricants was investigated. These lubricants are made with high viscosity index mineral oil base stock that offers excellent low-temperature characteristics, which improve low-temperature viscosity (lowering of operation temperature by 5 to 10°C), a 5% reduction of friction torque in manual and automatic transmission and power steering pump and increased oxidation resistance.