| 摘要 |
The present invention provides a lubricating oil composition that is for a trunk-piston-type diesel engine having superior high-temperature cleanliness and low occurrence of deposits even if a group II or group III base oil is used, wherein the composition results from (D) a metal-based cleaning agent and (E) an ashless dispersant being combined with a base oil having a kinematic viscosity at 100°C of 5-16 mm2/s and containing: (A) a mineral-oil-based lubricating base oil having at least 90 mass% of saturated hydrocarbons, no greater than 0.03 mass% of sulfur in terms of the amount of the element, a viscosity index of at least 80, and a kinematic viscosity at 100°C of 3-35 mm2/s; and (B) at least 5 mass% on the basis of the total amount of base oil of an extract (B1) having a %CA arising as a byproduct during solvent refining in the process of producing a mineral-oil-based lubricating base oil of at least 15%, or at least 20 mass% on the basis of the total amount of base oil of a mineral-oil-based lubricating base oil (B2) having less than 90 mass% of saturated hydrocarbons, over 0.03 mass% of sulfur in terms of the amount of the element, and a kinematic viscosity at 100°C of at least 30 mm2/s. |
