Lubricating oil composition for diesel engine

Abstract

The invention provides lubricant compositions for diesel engines having a regenerative DPF, which prolong life of the DPF by inhibiting accumulation of components depositable on DPF inner walls, diesel engine system shaving a regenerative DPF with prolonged life, and a method for inhibiting accumulation of components depositing on the DPF in the system. The present composition is for diesel engines having a regenerative DPF and running on diesel fuel with <10 mass ppm sulfur, contains a base oil and additives including (A) metal detergent, (B) ashless dispersant, and (C) phosphorus-based anti-wear agent, and satisfies the conditions of a sulfated ash content of 0.4-2 mass %, an atomic ratio of metal from component (A) to the total phosphorus of 0.2-3, an atomic ratio of the total boron to metal from component (A) of 0.2-2, and an atomic ratio of the total sulfur to metal from component (A) of 0-4.

1 . A lubricant composition for a diesel engine, said diesel engine being equipped with a regenerative DPF and running on diesel fuel with not more than 10 mass ppm sulfur, said lubricant composition comprising: 
 a lubricant base oil, and,    additives including:    (A) a metal detergent,    (B) an ashless dispersant, and    (C) a phosphorus-based anti-wear agent,    wherein said lubricant composition satisfies all of the following conditions (1) to (4):    (1) a sulfated ash content of 0.4 to 2 mass %,    (2) an atomic ratio of metal derived from component (A) to the total phosphorus (M/P ratio) of 0.2 to 3,    (3) an atomic ratio of the total boron to metal derived from component (A) (B/M ratio) of 0.2 to 2, and    (4) an atomic ratio of the total sulfur to metal derived from component (A) (S/M ratio) of 0 to 4.    
   
   
       2 . The lubricant composition according to  claim 1 , wherein said sulfated ash content as condition (1) is more than 0.8 mass % and not more than 1.2 mass %.  
   
   
       3 . The lubricant composition according to  claim 1 , wherein said sulfated ash content as condition (1) is 0.4 to 0.8 mass %.  
   
   
       4 . The lubricant composition according to  claim 1 , wherein said sulfated ash content as condition (1) is more than 1.2 mass % and not more than 2 mass %.  
   
   
       5 . The lubricant composition according to  claim 1 , wherein said metal detergent (A) includes at least one of alkaline earth metal salicylate and an overbased or basic salt thereof.  
   
   
       6 . The lubricant composition according to  claim 1 , wherein said regenerative DPF is a continuous regenerative DPF intended for mounting on a motor vehicle.  
   
   
       7 . A diesel engine system running on diesel fuel with not more than 10 mass ppm sulfur, comprising a regenerative DPF and a lubricant comprising a lubricant composition of  claim 1  as an engine lubricant.  
   
   
       8 . A method for inhibiting accumulation of a depositing component on a regenerative DPF in a diesel engine system, said method comprising running said engine system on diesel fuel with not more than 10 mass ppm sulfur, and operating said engine system using a lubricant composition of  claim 1  as a lubricant for said diesel engine system.