Idemitsu Kosan Company, Limited

Norihiro Kuroda

Hisao Anzai

Kenji Goto

Moritsugu Kasai

Shingo Onodera

Provided is a mineral base oil satisfying the following requirements (I) to (III): The foregoing mineral base oil can become a lubricating oil composition having desirable low-temperature viscosity characteristics, including low-temperature fuel consumption and low-temperature engine start-up performance, and also having excellent high-temperature piston detergency.

Mineral base oil, lubricant composition, internal combustion engine, lubricating method of internal combustion engine

Provided is a mineral base oil having a kinematic viscosity at 40&#xb0; C. of 4.0 mm/s or more and less than 6.0 mm/s, a kinematic viscosity at 100&#xb0; C. of 1.0 mm/s or more and less than 2.0 mm/s, and a flash point of 140&#xb0; C. or higher. A lubricating oil composition containing the mineral base oil has a high flash point while having a low viscosity and thus having excellent fuel-saving performance when used as a driving system oil and the like.

Mineral base oil and lubricating oil composition

A &#x3c0;-conjugated polymer composition including: (a) a solvent; (b) a &#x3c0;-conjugated polymer which is dissolved in the solvent and doped with a dopant; (c) at least one of an acidic substance and a salt of an acidic substance; and (d) a phenolic compound; wherein when only the acidic substance is contained as the component (c), the acidic substance is different from the phenolic compound, when only the salt of an acidic substance is contained, the salt of an acidic substance is different from the phenolic compound, and when both the acidic substance and the salt of an acidic substance are contained, at least one of the acidic substance and the salt of an acidic substance is different from the phenolic compound.

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Chiba, Japan

Norihiro Kuroda