Lubricating oil composition

Abstract

Provided is a lubricating oil composition for a gas engine, comprising a base oil (A), a calcium-based detergent (B), and an alkenyl succinimide (C), wherein a content of calcium atoms is 0.09 to 0.17 mass % based on the total amount of the lubricating oil composition, the component (C) comprises a non-boron-modified alkenyl bis-succinimide (C1), and a content of boron atoms derived from the component (C) is less than 0.02 mass % based on the total amount of the lubricating oil composition.

1 . A lubricating oil composition, comprising a base oil (A), a calcium-based detergent (B), and an alkenyl succinimide (C), wherein
 a content of the calcium-based detergent (B) in terms of calcium atoms is 0.09 to 0.17 mass % based on the total amount of the lubricating oil composition,   the alkenyl succinimide (C) comprises a non-boron-modified alkenyl bis-succinimide (C1), and   a content of boron atoms derived from the component alkenyl succinimide (C) is less than 0.02 mass % based on the total amount of the lubricating oil composition.   
     
     
         2 . The lubricating oil composition according to  claim 1 , wherein a content ratio [N/Ca] by mass of nitrogen atoms derived from the alkenyl succinimide (C) to calcium atoms derived from the calcium-based detergent (B) is 0.90 or less. 
     
     
         3 . The lubricating oil composition according to  claim 1 , wherein the calcium-based detergent (B) comprises calcium salicylate (B1). 
     
     
         4 . The lubricating oil composition according to  claim 1 , wherein the component non-boron-modified alkenyl bis-succinimide (C1) is a non-boron-modified alkenyl bis-succinimide at least having a polybutenyl group or a polyisobutenyl group having a weight-average molecular weight of 500 to 3000. 
     
     
         5 . The lubricating oil composition according to  claim 1 , wherein the alkenyl succinimide (C) further comprises a boron-modified alkenyl succinimide (C2) together with the component non-boron-modified alkenyl bis-succinimide (C1). 
     
     
         6 . The lubricating oil composition according to  claim 5 , wherein a content ratio [B/N] by mass of boron atoms derived from the boron-modified alkenyl succinimide (C2) to nitrogen atoms derived from the alkenyl succinimide (C) is 0.01 to 0.35. 
     
     
         7 . The lubricating oil composition according to  claim 1 , wherein a content of the alkenyl succinimide (C) in terms of nitrogen atoms is 0.005 to 0.15 mass % based on the total amount of the lubricating oil composition. 
     
     
         8 . The lubricating oil composition according to  claim 1 , further comprising zinc dithiophosphate (D). 
     
     
         9 . The lubricating oil composition according to  claim 1 , wherein a content of magnesium atoms is less than 0.04 mass % based on the total amount of the lubricating oil composition. 
     
     
         10 . The lubricating oil composition according to  claim 1 , wherein a content of molybdenum atoms is less than 0.01 mass % based on the total amount of the lubricating oil composition. 
     
     
         11 . A gas engine, comprising the lubricating oil composition according to  claim 1 . 
     
     
         12 . A method, comprising:
 applying the lubricating oil composition according to  claim 1  to a gas engine.