Lubricating oil compositions

Abstract

A crankcase lubricating oil composition for the crankcase of a spark-ignited or compression-ignited internal combustion engine, comprising a magnesium-containing detergent, in an amount sufficient to provide from 200-4000 ppm magnesium to the lubricating oil composition, in combination with an oil-soluble or oil-dispersible molybdenum compound in an amount sufficient to provide from 600-1500 ppm molybdenum atoms to the lubricating oil composition, and with an oil-soluble or oil-dispersible boron-containing compound in an amount sufficient to provide from 200-600 ppm boron atoms to the lubricating oil composition to improve the friction and fuel economy performance.

Claims

1. A crankcase lubricating oil composition comprising or made by admixing: (A) an oil of lubricating viscosity, in a major amount; (B) an oil-soluble or oil-dispersible molybdenum dithiocarbamate additive, providing from 700-1000 ppm of molybdenum atoms to the lubricating oil composition; (C) a detergent composition comprising one or more overbased magnesium sulfonate detergents having or having on average a TBN of 150 to 500 mgKOH/g, in an amount providing from 450-1200 ppm of magnesium atoms to the lubricating oil composition, measured according to ASTM D5185; and (D) an oil-soluble or oil-dispersible boron-containing succinimide dispersant compound present in the lubricating oil composition in an amount sufficient to provide from 200-400 ppm boron atoms to the lubricating oil composition, measured according to ASTM D5185.

2. A lubricating oil composition according to claim 1, wherein the detergent composition comprises one or more additional detergent additive selected from magnesium salicylate, calcium salicylate, calcium sulfonate, magnesium phenate, and calcium phenate, hybrid detergents comprising two or more of these additional detergent additives and/or combinations thereof.

3. A lubricating oil composition according to claim 2, wherein the detergent composition further comprises at least one detergent selected from calcium salicylate detergent and calcium sulfonate detergent.

4. A lubricating oil composition according to claim 3, wherein the detergent composition consists of one or more overbased magnesium sulfonate detergents and one or more calcium salicylate detergents.

5. A lubricating oil composition according to claim 3, wherein calcium-containing detergent is present in an amount sufficient to provide from 900-2000 ppm atomic calcium to the lubricating oil composition, measured according to ASTM D5185.

6. A lubricating oil composition according to claim 4, wherein calcium-containing detergent is present in an amount sufficient to provide 900-2000 ppm atomic calcium to the lubricating oil composition, measured according to ASTM D5185.

7. A method of lubricating a spark-ignited or compression-ignited internal combustion engine comprising lubricating the engine with a lubricating oil composition as defined in accordance with claim 1.

8. A method of lubricating a spark-ignited or compression-ignited internal combustion engine comprising lubricating the engine with a lubricating oil composition as defined in accordance with claim 4.

9. A method of lubricating a spark-ignited or compression-ignited internal combustion engine comprising lubricating the engine with a lubricating oil composition as defined in accordance with claim 6.

Description

EXAMPLES

(1) The invention will now be described in the following examples which are not intended to limit the scope of the claims hereof.

(2) A series of oils were testing in the High Frequency Reciprocating Rig (HFRR-supplied by PCS Instruments) to evaluate the boundary regime friction characteristics of the oils.

(3) The rig was set up with a 6 mm ball on a 10 mm disc. The test protocol employed was as follows:

(4) TABLE-US-00003 Test Duration (mins) 1 min hold and 5 min run at each s temperature tage Test Load (N) 4 Frequency (Hz) 40 Stroke Length (microns) 1,000 Temperature ( C.) 40, 60, 80, 100, 120, 140

(5) The test has 6 temperature stages and you can record the average friction at each temperature stage and the overall average friction across all stages.

(6) Four comparative oils (indicated by the C- prefix) and five oils according to the invention (indicated by the I- prefix) were tested. The composition of each oil is set out in Table I below, together with the average HFRR friction across the all stages of the test and the low temperature HFRR friction, which is the average of the 40 C. and 60 C. stages of the test.

(7) A comparison of Oil C-1, Oil C-3 and Oil I-3 shows that inclusion of high levels of molybdenum in a lubricating oil comprising either magnesium or calcium detergents improves the average HFRR friction performance of the oil, as expected. A comparison of Oil C-3 and Oil I-3 also shows that this is further improved when the calcium detergent is replaced by a magnesium detergent. This further improvement resulting from the replacement of the calcium detergent with a magnesium detergent is unexpected.

(8) A comparison of Oil C-3 and Oil C-4 and a comparison of Oil I-1 and Oil I-3 shows that in the presence of high treat rate of molybdenum, addition of significant treat rates of boron also improves the HFRR friction performance, which is unexpected.

(9) A comparison of Oil I-1 and Oil I-2 shows that changing the magnesium salicylate detergent to a magnesium sulfonate detergent in otherwise comparable oils significantly improves the low temperature friction performance, whilst maintaining the improved performance exhibited by use of the magnesium detergent compared to the calcium detergent referred to above. This improvement in low temperature friction performance is unexpected.

(10) Finally, a comparison of Oil I-4 and Oil I-5 shows that the best improvement of average HFRR friction can be obtained when a combination of calcium and magnesium detergent is used, and again the presence of magnesium sulfonate detergent in the calcium/magnesium detergent mixture further improves the low temperature friction performance.

(11) TABLE-US-00004 TABLE 1 Oil C-1 Oil C-2 Oil C-3 Oil C-4 Oil I-1 Oil I-2 Oil I-3 Oil I-4 Oil I-5 Component Mass % Mass % Mass % Mass % Mass % Mass % Mass % Mass % Mass % Molybdenum Compound.sup.1 0 0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Calcium Salicylate.sup.2 0 0 1.75 1.75 0 0 0 0.84 0.88 Magnesium Salicylate.sup.3 0.73 0.73 0 0 0.73 0 0.73 0.39 0 Magnesium Sulfonate.sup.4 0 0 0 0 0 0.65 0 0 0.33 Borated dispersant.sup.5 0 0.55 0 0.55 0.55 0.55 0 0.55 0.55 Additional Additives.sup.6 3.39 3.39 3.39 3.39 3.39 3.39 3.39 3.39 3.39 Mo, ppm (ASTM D5185) 0 0 980 980 980 980 980 980 980 B, ppm (ASTM D5185) 0 299 0 299 299 299 0 299 299 Mg, mass % (ASTM D5185) 0.10 0.10 0 0 0.10 0.10 0.10 0.05 0.05 Ca, mass % (ASTM D5185) 0 0 0.2 0.2 0 0 0 0.11 0.10 P, mass % (ASTM D5185) 0.075 0.075 0.075 0.075 0.075 0.075 0.075 0.075 0.075 SASH, mass %(ASTM D374) 0.6 0.6 0.8 0.9 0.6 0.6 0.6 0.7 0.7 Average HFRR friction 0.156 0.158 0.100 0.082 0.081 0.080 0.086 0.070 0.077 Low temperature HFFR friction 0.136 0.141 0.122 0.111 0.085 0.078 0.098 0.086 0.074 .sup.1The molybdenum compound was Infincum C9401, a dimeric molybdenum dithiocarbamate available from Infincum UK Ltd. .sup.2The calcium salkylate was a Infincum C9329 an overbased detergent having a TBN of 229 and 8 mass % Ca available from Infincum UK Ltd .sup.3The magnesium salicylate was Infincum C9012 an overbased detergent having a TBN of 342 and 7.4 mass % Mg available from Infincum UK Ltd .sup.4The magnesium sulfonate was Infincum C9340 and overbased detergent having a TBN of 400 and 9.1 mass % Mg available from Infincum UK Ltd .sup.5The borated dispersant was Infincum C9202 a borated ashless polyisobutenyl succimimide dispersant containing 2.3 mass % B available from Infincum UK Ltd .sup.6The additional additives are provided by a detergent inhibitor package comprising non-borated dispersant, zinc dialkyldithiophosphate, and antioxidant. The amount of each of these additives was the same in each oil tested.