Low sulfur, low sulfated ash, low phosphorus and highly paraffinic lubricant composition

Abstract

The present invention relates to a lubricant composition having a sulphur content of from 0.01 to 0.3 wt. %, a phosphorus content of from 0.01 to 0.1 wt. % and a sulphated ash content of from 0.1 to 1.2 wt. %, based on the total weight of the lubricant composition, which comprises a base oil or base oil blend, wherein the lubricant composition has a kinematic viscosity at 100° C. of more than 5.0 mm 2 /s (cSt), a cold cranking simulated dynamic viscosity at −15° C. according to ASTM D 5293 of less than 9500 mPas (cP) and a mini rotary viscosity test value of less than 60000 mPas at −20° C. according to ASTM D 4684, and wherein the base oil or base oil blend comprises a continuous series of iso-paraffins having n, n+1, n+2, n+3 and n+4 carbon atoms. The invention relates further to the use of the lubricant composition, for the reduction of piston ring deposits in an internal combustion engine.

1 . A lubricant composition having a sulphur content of from 0.01 to 0.3 wt. %, a phosphorus content of from 0.01 to 0.1 wt. % and a sulphated ash content of from 0.1 to 1.2 wt. %, based on the total weight of the lubricant composition, which comprises a base oil or base oil blend, wherein the lubricant composition has a kinematic viscosity at 100° C. of more than 5.0 mm 2 /s (cSt), a cold cranking simulated dynamic viscosity at −15° C. according to ASTM D 5293 of less than 9500 mPas (cP) and a mini rotary viscosity test value of less than 60000 mPas at −20° C. according to ASTM D 4684, and wherein the base oil or base oil blend comprises a continuous series of iso-paraffins having n, n+1, n+2, n+3 and n+4 carbon atoms, wherein n is between 15 and 35. 
   
   
       2 . The lubricant composition according to  claim 1 , wherein the base oil or base oil blend has a pour point of less than −39° C. and a kinematic viscosity at 100° C. of between 3.8 and 8.5 mm 2 /s (cSt), and wherein the lubricant composition has a kinematic viscosity at 100° C. of between 9.3 and 16.3 mm 2 /s (cSt). 
   
   
       3 . The lubricant composition according to  claim 1 , wherein the base oil or base oil blend comprises at least 98 wt % saturates and wherein the saturates fraction consists of between 10 and 40 wt % of cyclo-paraffins. 
   
   
       4 . The lubricant composition according to  claim 3 , wherein the saturates fraction consists of more than 12 wt % of cyclo-paraffins. 
   
   
       5 . The lubricant composition according to  claim 1 , wherein the base oil or base oil blend is obtainable from a process comprising the following steps:
 (a) hydrocracking/hydroisomerisating a Fischer-Tropsch product having a weight ratio of compounds having at least 60 or more carbon atoms and compounds having at least 30 carbon atoms of at least 0.2 and wherein at least 30 wt % of compounds in the Fischer-Tropsch product have at least 30 carbon atoms,   (b) separating the product of step (a) into at least one or more fuel fractions and a base oil precursor fraction, and   (c) performing a catalytic dewaxing step to the base oil precursor fraction obtained in step (b), and optionally   (d) separating the products obtained in step (c) into at least one or more base oil fractions, and a lower boiling fraction.   
   
   
       6 . The lubricant composition according to  claim 1 , wherein the Fischer-Tropsch product used in step (a) has at least 50 wt %, of compounds having at least 30 carbon atoms and wherein the weight ratio of compounds having at least 60 or more carbon atoms to compounds having at least 30 carbon atoms of the Fischer-Tropsch product is at least 0.4 and wherein the Fischer-Tropsch product comprises a C20+ fraction having an ASF-alpha value (Anderson-Schulz-Flory chain growth factor) of at least 0.925. 
   
   
       7 . The lubricant composition according to  claim 1 , wherein the composition further comprises one or more zinc dithiophosphates. 
   
   
       8 . The lubricant composition according to  claim 1 , wherein said composition further comprises one or more salicylate detergents. 
   
   
       9 . The lubricant composition according to  claim 1 , wherein said lubricant composition has a sulphated ash content in the range of 0.6 to 1.0 wt. %, based on the total weight of the lubricant composition. 
   
   
       10 . The lubricant composition according to  claim 1 , having a sulphur content in the range of 0.12 to 0.20 wt. %, based on the total weight of the lubricant composition. 
   
   
       11 . The lubricant composition according to  claim 1 , having a TBN value in the range of from 5.0 to 12.0 mg·KOH/g, as measured by ASTM D2896. 
   
   
       12 . The lubricant composition according to  claim 1 , having a Top Groove fill in of below 50% vol. according to the Nissan TD25 Detergency Test (Japanese Automobile Standards Organization (JASO) M336:1998). 
   
   
       13 . The lubricant composition according to  claim 1 , having a residual carbon content of less than 4.8% wt. according to the Nissan TD25 Detergency Test (Japanese Automobile Standards Organization (JASO) M336:1998). 
   
   
       14 . A method of lubricating an internal combustion engine with a lubricant composition according to  claim 1 , wherein the lubricant composition yields a Top Groove fill in of below 50% vol. according to the Nissan TD25 Detergency Test (Japanese Automobile Standards Organization (JASO) M336:1998). 
   
   
       15 . The use of a lubricant composition according to  claim 1  to improve engine cleanliness in diesel, gas-fuelled or gasoline engine applications, wherein the lubricant composition yields a residual carbon content of less than 4.8% wt. according to the Nissan TD25 Detergency Test (Japanese Automobile Standards Organization (JASO) M336:1998). 
   
   
       16 . A method of improving piston cleanliness and reducing the ring-sticking tendencies of a compression-ignited internal combustion engine according to the Nissan TD25 Detergency Test (Japanese Automobile Standards Organization (JASO) M336:1998) comprising adding to the engine a lubricant composition according to  claim 1 .