Lubricating compositions and methods of operating an internal combustion engine

Abstract

The instant disclosure generally relates to lubricating compositions having an oil of lubricating viscosity, a mixture of boron-containing and boron-free dispersants, an overbased magnesium-based detergent, an overbased calcium-based detergent, an ashless friction modifier, and, optionally, other performance additives. The instant lubricating compositions may improve one or more of cleanliness, TBN retention, fuel economy and low-speed preignition (“LSPI”).

1 . An internal combustion engine lubricating composition comprising:
 oil of lubricating viscosity comprising at least 50 weight percent of a Group III base oil, a Group IV base oil, or combinations thereof;   a boron-containing polyisobutenyl succinimide dispersant;   a boron-free polyisobutenyl succinimide dispersant;   an overbased magnesium-based detergent in an amount to deliver at least 400 ppm magnesium to the lubricating composition;   an overbased calcium-based detergent in an amount to deliver at least 400 ppm calcium to the lubricating composition; and   an ashless friction modifier.   
     
     
         2 . The lubricating composition according to  claim 1 , wherein the boron-containing succinimide dispersant is derived from a polyisobutylene having a vinylidene content of greater than 70 mol % and the dispersant has a number average molecular weight of from 1750 to 220. 
     
     
         3 . (canceled) 
     
     
         4 . The lubricating composition according to  claim 1 , wherein the boron-containing succinimide dispersant is present in the lubricating composition in an amount of from 0.2 to 2.1 wt %. 
     
     
         5 .- 7 . (canceled) 
     
     
         8 . The lubricating composition according to  claim 1 , wherein the boron-free polyisobutenyl succinimide dispersant has a number average molecular weight of from 750 to 2500. 
     
     
         9 . The lubricating composition according to  claim 1 , wherein the boron-free polyisobutenyl succinimide dispersant is present in the lubricating composition in an amount 0.5 to 6.5 wt %. 
     
     
         10 .- 13 . (canceled) 
     
     
         14 . The lubricating composition according to  claim 1 , wherein the boron-free polyisobutenyl succinimide dispersant includes a first boron-free polyisobutenyl succinimide dispersant having a number average molecular weight of from 750 to 1750 and is present in the lubricating composition in an amount of from 0.5 to 4.5 and a second boron-free polyisobutenyl succinimide dispersant having a number average molecular weight of from 1950 to 2500 and is present in the lubricating composition in an amount of from 0.2 to 2.0. 
     
     
         15 .- 16 . (canceled) 
     
     
         17 . The lubricating composition according to  claim 1 , wherein the overbased magnesium-based detergent is present in the lubricating composition in an amount of from 0.1 to 1.5 wt %. 
     
     
         18 .- 19 . (canceled) 
     
     
         20 . The lubricating composition according to  claim 1  wherein the overbased magnesium-based detergent is an overbased alkylbenzene sulfonate detergent having a metal ratio of at least 8. 
     
     
         21 . The lubricating composition according to  claim 1 , wherein the overbased magnesium-based detergent has a TBN (KOH/g) greater than 500. 
     
     
         22 . The lubricating composition according to  claim 1 , wherein the overbased magnesium-based detergent has a TBN (KOH/g) of from 500 to 850. 
     
     
         23 .- 24 . (canceled) 
     
     
         25 . The lubricating composition according to  claim 1 , wherein the overbased magnesium-based detergent delivers from 400 to 700 ppm magnesium to the lubricating composition. 
     
     
         26 . The lubricating composition according to  claim 1 , wherein the overbased calcium-based detergent is present in the lubricating composition in an amount of from 0.1 to 2.5 wt %. 
     
     
         27 .- 29 . (canceled) 
     
     
         30 . The lubricating composition according to  claim 1 , wherein the overbased calcium-based detergent has a metal ratio of at least 5. 
     
     
         31 . The lubricating composition according to  claim 1 , wherein the overbased calcium-based detergent has a TBN (KOH/g) from 450 to 850. 
     
     
         32 .- 33 . (canceled) 
     
     
         34 . The lubricating composition according to  claim 1 , wherein the overbased calcium-based detergent delivers from 400 to 700 ppm calcium to the lubricating composition. 
     
     
         35 . The lubricating composition according to  claim 1 , wherein the overbased calcium-based detergent is selected from an overbased calcium salixarate detergent, an overbased calcium salicylate detergent, or mixtures thereof. 
     
     
         36 . The lubricating composition according to  claim 1 , wherein the overbased calcium-based detergent is an overbased calcium salicylate detergent. 
     
     
         37 . The lubricating composition according to  claim 1 , wherein the overbased calcium-based detergent includes a mixture of an overbased calcium salixarate detergent and an overbased calcium salicylate detergent. 
     
     
         38 . The lubricating composition according to  claim 1 , further comprising an ashless antioxidant present in an amount of at least 0.9 weight percent of the lubricating composition. 
     
     
         39 .- 40 . (canceled) 
     
     
         41 . The lubricating composition according to  claim 1 , wherein the ashless friction modifier includes one or more of an ester, an amide, or an imide of an alpha-hydroxy carbonyl compound, and mixtures thereof. 
     
     
         42 . The lubricating composition according to  claim 1 , wherein the ashless friction modifier is present in the lubricating composition in an amount of from 0.01 to 1.1 wt %. 
     
     
         43 .- 44 . (canceled) 
     
     
         45 . The lubricating composition according to  claim 1 , further comprising a zinc dialkyldithiophosphate anti-wear agent in an amount to deliver 200 ppm up to 1000 ppm phosphorus to the lubricating composition. 
     
     
         46 .- 47 . (canceled) 
     
     
         48 . The lubricating composition according to  claim 1 , wherein the lubricating composition is free of or substantially free of tetrapropenylphenol (pddp) and derivatives thereof. 
     
     
         49 . (canceled) 
     
     
         50 . A method of operating a gasoline-fueled internal combustion engine comprising supplying to an internal combustion engine a lubricating composition according to  claim 1 . 
     
     
         51 . (canceled) 
     
     
         52 . A method for reducing low speed preignition in a gasoline-fueled internal combustion engine operating at a brake mean effective pressure (BMEP) of greater than 12 bars and at a speed of less than 3,000 RPMs comprising: supplying to said engine a lubricating composition according to  claim 1 . 
     
     
         53 . The method of  claim 52  where the gasoline-fueled internal combustion engine further comprises a turbo charger. 
     
     
         54 .- 55 . (canceled)