Lubricating oil composition

Abstract

A lubricating oil composition is provided, which can reduce friction even when the viscosity is lowered. A lubricating oil composition comprising a lubricating base oil, (A) a cleaning agent containing magnesium, and (B) a zinc dialkyl dithiophosphate, wherein the amount of component (A) is 200 to 1200 ppm by weight of magnesium per total weight of lubricating oil composition; the amount of component (B) is 300 to 1000 ppm by weight phosphorus based on total weight of lubricating oil composition; wherein component (B) comprises (B-1) a zinc dialkyl dithiophosphate having a primary alkyl group, and the proportion of the weight of component (B-1) to the total weight of component (B) is 30 weight % or more; and the concentration of boron [B] is less than 100 ppm by weight.

1 . A lubricating oil composition comprising a lubricating base oil,
 (A) a cleaning agent containing magnesium, and (B) a zinc dialkyl dithiophosphate,
 wherein an amount of component (A) in terms of ppm by weight of magnesium ([Mg]) based on a total weight of the lubricating oil composition is in a range of 200 to 1200 ppm by weight; an amount of component (B) in terms of ppm by weight of phosphorus ([P]) based on the total weight of the lubricating oil composition is in a range of 300 to 1000 ppm by weight; 
 wherein component (B) comprises (B-1) a zinc dialkyl dithiophosphate having a primary alkyl group, and a proportion of a weight of component (B-1) to a total weight of component (B) is 30 weight % or more; and 
 wherein a concentration of boron [B] in terms of ppm by weight of boron based on the total weight of the lubricating oil composition is less than 100 ppm by weight. 
   
     
     
         2 . The lubricating oil composition according to  claim 1 , further comprising (C) a dispersant, wherein an amount of component (C) is 0.1 to 8 weight % based on the total weight of the lubricating oil composition. 
     
     
         3 . The lubricating oil composition according to  claim 1 , which further comprises (A′) a cleaning agent containing calcium, and satisfies following formula (1):
   {[Mg]/([Mg]+[Ca])}×100≥5  (1)
 
 
       wherein [Ca] represents a weight of calcium in terms of ppm based on the total weight of the lubricating oil composition. 
     
     
         4 . The lubricating oil composition according to  claim 1 , further comprising (D) a friction modifier containing molybdenum, wherein an amount of component (D) is in a range of 200 to 1400 ppm by weight in terms of a ppm by weight of molybdenum ([Mo]) based on the total weight of the lubricating oil composition. 
     
     
         5 . The lubricating oil composition of  claim 1 , further comprising a viscosity index improver, wherein an amount of the viscosity index improver in terms of a weight of polymer contained in the viscosity index improver based on the total weight of the lubricating oil composition is 1 weight % or less. 
     
     
         6 . The lubricating oil composition according to  claim 1 , having a CCS viscosity at −35° C. of 6.2 Pa·s or less. 
     
     
         7 . The lubricating oil composition according to  claim 1 , having a high temperature high shear viscosity (HTHS viscosity) at 150° C. of not less than 1.3 mPa·s but less than 2.3 mPa·s. 
     
     
         8 . The lubricating oil composition according to  claim 1 , having a kinematic viscosity at 100° C. of less than 6.1 mm 2 /s. 
     
     
         9 . The lubricating oil composition according to  claim 1 , which is for an internal combustion engine. 
     
     
         10 . The lubricating oil composition according to  claim 1 , which is for a supercharged gasoline engine. 
     
     
         11 . The lubricating oil composition according to  claim 2 , which further comprises (A′) a cleaning agent containing calcium, and satisfies following formula (1):
   {[Mg]/([Mg]+[Ca])}×100≥5  (1)
 
 
       wherein [Ca] represents a weight of calcium in terms of ppm based on the total weight of the lubricating oil composition. 
     
     
         12 . The lubricating oil composition according to  claim 2 , further comprising (D) a friction modifier containing molybdenum, wherein an amount of component (D) is in a range of 200 to 1400 ppm by weight in terms of a ppm by weight of molybdenum ([Mo]) based on the total weight of the lubricating oil composition. 
     
     
         13 . The lubricating oil composition according to  claim 3 , further comprising (D) a friction modifier containing molybdenum, wherein an amount of component (D) is in a range of 200 to 1400 ppm by weight in terms of a ppm by weight of molybdenum ([Mo]) based on the total weight of the lubricating oil composition. 
     
     
         14 . The lubricating oil composition of  claim 2 , further comprising a viscosity index improver, wherein an amount of the viscosity index improver in terms of a weight of polymer contained in the viscosity index improver based on the total weight of the lubricating oil composition is 1 weight % or less. 
     
     
         15 . The lubricating oil composition of  claim 3 , further comprising a viscosity index improver, wherein an amount of the viscosity index improver in terms of a weight of polymer contained in the viscosity index improver based on the total weight of the lubricating oil composition is 1 weight % or less. 
     
     
         16 . The lubricating oil composition of  claim 4 , further comprising a viscosity index improver, wherein an amount of the viscosity index improver in terms of a weight of polymer contained in the viscosity index improver based on the total weight of the lubricating oil composition is 1 weight % or less.