Idemitsu Kosan Company, Limited

Yumiko Kiko

Tahei Okada

A lubricating oil composition containing a base oil having a kinematic viscosity at 40 degrees C. in a range from 10 mm/s to 1000 mm/s with: (A) at least one of phosphorus compounds represented by a formula (1) in an amount of 0.001 mass % to 0.3 mass % in terms of a phosphorus content; (B) at least one of a sulfur compound represented by a formula (2) and a sulfur compound that comprises a dithio (&#x2014;S&#x2014;S&#x2014;) bond in a molecule in an amount of 0.01 mass % to 0.5 mass % in terms of a sulfur content, the latter sulfur compound, when added to the base oil in an amount of 1 mass %, leading to a rating of 2 or lower in a copper strip corrosion test; and (D) a succinimide derivative in an amount of 0.01 mass % to 1 mass %. 

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Ichihara, Japan

Yumiko Kiko