Lubricant composition for gasoline engine and method for producing same

Abstract

Provided is a lubricating oil composition having excellent detergency and LSPI preventing performance, and specifically a lubricating oil composition including a base oil, a calcium detergent, and a magnesium detergent and/or a sodium detergent, wherein the content of the calcium detergent as converted into a calcium atom and a mass ratio of a magnesium atom (Mg) contained in the magnesium detergent and/or a sodium atom (Na) contained in the sodium detergent to a calcium atom (Ca) [(Mg and/or Na)/Ca] fall within the specific ranges.

1 : A lubricating oil composition, comprising a base oil, a calcium detergent, and a magnesium detergent and/or a sodium detergent, wherein
 a content of the calcium detergent as converted into a calcium atom is less than 2,000 ppm by mass on a basis of the whole amount of the composition, and   a mass ratio of a magnesium atom (Mg) contained in the magnesium detergent and/or a sodium atom (Na) contained in the sodium detergent to a calcium atom (Ca) [(Mg and/or Na)/Ca] is 0.05 to 1.50.   
     
     
         2 : The lubricating oil composition according to  claim 1 , further comprising a poly(meth)acrylate. 
     
     
         3 : The lubricating oil composition according to  claim 1 , wherein the content of the calcium detergent as converted into a calcium atom is 800 to 1,800 ppm by mass on a basis of the whole amount of the composition. 
     
     
         4 : The lubricating oil composition according to  claim 1 , wherein a content of the magnesium detergent and/or the sodium detergent as converted to a magnesium atom and/or a sodium atom is 100 ppm by mass or more on a basis of the whole amount of the composition. 
     
     
         5 : The lubricating oil composition according to  claim 1 , wherein a content of the magnesium detergent and/or the sodium detergent as converted to a magnesium atom and/or a sodium atom is 100 to 1,500 ppm by mass on a basis of the whole amount of the composition. 
     
     
         6 : The lubricating oil composition according to  claim 1 , further comprising a succinimide and/or a boron-containing succinimide. 
     
     
         7 : The lubricating oil composition according to  claim 6 , wherein a content of nitrogen in the composition is less than 0.16 mass %. 
     
     
         8 : The lubricating oil composition according to  claim 6 , wherein a content of the boron-containing succinimide as converted into a boron atom is 600 ppm by mass or less on a basis of whole amount of the composition. 
     
     
         9 : The lubricating oil composition according to  claim 1 , wherein a total base number of at least one of the magnesium detergent and the sodium detergent by the perchloric acid method as prescribed in JIS K2501 is 150 to 650 mg/KOH. 
     
     
         10 : The lubricating oil composition according to  claim 1 , wherein the content of the calcium detergent as converted into a calcium atom is 800 ppm by mass or more on a basis of the whole amount of the composition. 
     
     
         11 : The lubricating oil composition according to  claim 1 , wherein the content of the calcium detergent as converted into a calcium atom is 800 to 1,500 ppm by mass or more on a basis of the whole amount of the composition. 
     
     
         12 : The lubricating oil composition according to  claim 1 , wherein a content of the magnesium detergent and/or the sodium detergent as converted to a magnesium atom and/or a sodium atom is 300 to 1,000 ppm by mass on a basis of the whole amount of the composition. 
     
     
         13 : The lubricating oil composition according to  claim 1 , wherein the base oil is at least one selected from the group consisting of a mineral oil and a synthetic oil which are classified into Groups 3 to 5 of the base stock categories of the API (American Petroleum Institute). 
     
     
         14 : The lubricating oil composition according to  claim 1 , which has a kinematic viscosity at 100° C. of 3.8 to 12.5 mm 2 /s. 
     
     
         15 : The lubricating oil composition according to  claim 1 , which is suitable for a gasoline engine mounted with a direct injection supercharger. 
     
     
         16 : A method for producing a lubricating oil composition, the method comprising:
 blending a base oil with a calcium detergent and a magnesium detergent and/or a sodium detergent, such that   a content of the calcium detergent as converted into a calcium atom is less than 2,000 ppm by mass on a basis of the whole amount of the composition, and   a mass ratio of a magnesium atom (Mg) contained in the magnesium detergent and/or a sodium atom (Na) contained in the sodium detergent to a calcium atom (Ca) [(Mg and/or Na)/Ca] is 0.05 to 1.50.