Cylinder lubricating oil composition for crosshead diesel engine

Abstract

The present invention relates to a cylinder lubricating oil for crosshead diesel engines. In addition to having conventional characteristics such as heat resistance, cleanliness, wear resistance, and the like, the cylinder lubricating oil can be used with fuel of any sulfur content and suppresses the amount of piston deposit even when the base number is excessive. In greater detail, the present invention relates to a cylinder lubricating oil composition which includes an ashless dispersant (B) and a metallic detergent (C) in a lubricant base oil (A), in which the product of the number average molecular weight, the content, and the effective concentration of the ashless dispersant (B) is at least 9000, and the endothermic peak temperature of the metallic detergent (C) as measured by DSC at a rate of temperature increase of 50° C./min is at most 460° C.

1 . A cylinder lubricating oil composition for a crosshead diesel engine, comprising an ashless dispersant (B) and a metallic detergent (C) in a lubricant base oil (A), wherein
 a product of a number average molecular weight, a content, and an effective concentration of the ashless dispersant (B) is at least 9000, and   an endothermic peak temperature of the metallic detergent (C) as measured by DSC at a rate of temperature increase of 50° C./min is at most 460° C.   
     
     
         2 . The cylinder lubricating oil composition for a crosshead diesel engine according to  claim 1 , wherein the number average molecular weight of the ashless dispersant (B) is at least 2500.