Lubricant oil composition and method for manufacturing same

Abstract

To provide a lubricating oil composition that has good detergency irrespective of the small sulfated ash content thereof, and has a good friction reducing capability even after the deterioration thereof. The lubricating oil composition contains a base oil (A), a non-metal-containing sulfur antioxidant (B), and a hindered amine antioxidant (C) having one piperidine-derived skeleton in a molecule, and has a content of the non-metal-containing sulfur antioxidant (B) as converted in terms of sulfur atom of 800 ppm by mass or more based on the total amount of the lubricating oil composition, a content of the hindered amine antioxidant (C) as converted in terms of nitrogen atom of 100 ppm by mass or more and 400 ppm by mass or less based on the total amount of the lubricating oil composition, a sulfated ash content of 0.70% by mass or less, and a total base number of 4.0 mgKOH/g or more.

1 . A lubricating oil composition, comprising:
 (A) a base oil (A);   (B) a non-metal-containing sulfur antioxidant (B); and   (C) a hindered amine antioxidant (C) having one piperidine-derived skeleton in a molecule,   wherein:   a content of the non-metal-containing sulfur antioxidant (B) as converted in terms of sulfur atom of 800 ppm by mass or more based on the total amount of the lubricating oil composition;   a content of the hindered amine antioxidant (C) as converted in terms of nitrogen atom of 100 ppm by mass or more and 400 ppm by mass or less based on the total amount of the lubricating oil composition;   a sulfated ash content of 0.70% by mass or less; and   a total base number of 4.0 mgKOH/g or more.   
     
     
         2 . The lubricating oil composition according to  claim 1 , wherein the non-metal-containing sulfur antioxidant (B) is at least one selected from the group consisting of a thiocarbamate compound, a thiadiazole compound, a polysulfide compound, and a sulfurized fat or fatty oil. 
     
     
         3 . The lubricating oil composition according to  claim 1 , wherein the content of the non-metal-containing sulfur antioxidant (B) as converted in terms of sulfur atom is 1,200 ppm by mass or more and 6,500 ppm by mass or less based on the total amount of the lubricating oil composition. 
     
     
         4 . The lubricating oil composition according to  claim 1 , wherein the content of the hindered amine antioxidant (C) as converted in terms of nitrogen atom is 200 ppm by mass or more and 400 ppm by mass or less based on the total amount of the lubricating oil composition. 
     
     
         5 . The lubricating oil composition according to  claim 1 , further comprising:
 (D) a metal-based detergent (D),   
       wherein a content of the metal-based detergent (D) as converted in terms of metal atom of 700 ppm by mass or more and 1,400 ppm by mass or less based on the total amount of the lubricating oil composition. 
     
     
         6 . The lubricating oil composition according to  claim 5 , wherein the ratio of the content of the hindered amine antioxidant (C) as converted in terms of nitrogen atom and the content of the metal-based detergent (D) as converted in terms of metal atom [(content of hindered amine antioxidant (C) as converted in terms of nitrogen atom)/(content of metal-based detergent (D) as converted in terms of metal atom)] is from 0.14 to 0.58. 
     
     
         7 . The lubricating oil composition according to  claim 1 , further comprising:
 (E) a molybdenum friction modifier (E),   
       wherein a content of the molybdenum friction modifier (E) as converted in terms of molybdenum atom of 300 ppm by mass or more and 1,300 ppm by mass or less based on the total amount of the lubricating oil composition. 
     
     
         8 . The lubricating oil composition according to  claim 7 , wherein the ratio of the content of the non-metal-containing sulfur antioxidant (B) as converted in terms of sulfur atom and the content of the molybdenum friction modifier (E) as converted in terms of molybdenum atom [(content of non-metal-containing sulfur antioxidant (B) as converted in terms of sulfur atom)/(content of molybdenum friction modifier (E) as converted in terms of molybdenum atom)] is from 0.92 to 13.35. 
     
     
         9 . The lubricating oil composition according to  claim 7 , wherein the ratio of the content of the hindered amine antioxidant (C) as converted in terms of nitrogen atom and the content of the molybdenum friction modifier (E) as converted in terms of molybdenum atom [(content of hindered amine antioxidant (C) as converted in terms of nitrogen)/(content of molybdenum friction modifier (E) as converted in terms of molybdenum atom)] is from 0.15 to 1.35. 
     
     
         10 . The lubricating oil composition according to  claim 1 , wherein the content of the base oil (A) is less than 90% by mass based on the total amount of the lubricating oil composition. 
     
     
         11 . A lubricating oil composition for an engine equipped with a forced-induction mechanism, the composition comprising the lubricating oil composition of  claim 1 . 
     
     
         12 . A method for producing a lubricating oil composition, the method comprising preparing a lubricating oil composition containing a base oil (A), a non-metal-containing sulfur antioxidant (B), a hindered amine antioxidant (C) having one piperidine-derived skeleton in a molecule, the preparing step being performed to satisfy the following conditions (i) to (iv):
 (i) the lubricating oil composition having a content of the non-metal-containing sulfur antioxidant (B) as converted in terms of sulfur atom of 800 ppm by mass or more based on the total amount of the lubricating oil composition,   (ii) the lubricating oil composition having a content of the hindered amine antioxidant (C) as converted in terms of nitrogen atom of 100 ppm by mass or more and 400 ppm by mass or less based on the total amount of the lubricating oil composition,   (iii) the lubricating oil composition having a sulfated ash content of 0.70% by mass or less, and   (iv) the lubricating oil composition having a total base number of 4.0 mgKOH/g or more.