COMPOSITIONS AND METHODS AND USES RELATING THERETO

Abstract

A quaternary ammonium compound of formula (I):

##STR00001##

wherein R.sup.0, R.sup.1, R.sup.2 and R.sup.3 is each independently an optionally substituted hydrocarbyl group, X is a linking group, R.sup.4 is an optionally substituted alkylene group, R.sup.5 is hydrogen or an optionally substituted alkyl, alkenyl or aryl group, and n is 0 or a positive integer, provided that n is not 0 when R.sup.5 is hydrogen.

Claims

1. A quaternary ammonium compound of formula (I): ##STR00017## wherein R.sup.0, R.sup.1, R.sup.2 and R.sup.3 is each independently an optionally substituted hydrocarbyl group, X is a linking group, R.sup.4 is an optionally substituted alkylene group, R.sup.5 is hydrogen or an optionally substituted alkyl, alkenyl or aryl group, and n is 0 or a positive integer, provided that n is not 0 when R.sup.5 is hydrogen.

2. A method of preparing a quaternary ammonium salt, the method comprising reacting (a) a tertiary amine of formula R.sup.1R.sup.2R.sup.3N with (b) an acid-derived alkylating agent in the presence of (c) a compound of formula HOOCXCOO(R.sup.4O).sub.nR.sup.5, wherein R.sup.4 is an optionally substituted alkylene group, R.sup.5 is hydrogen or an optionally substituted alkyl, alkenyl or aryl group, and n is 0 or a positive integer, provided that n is not 0 when R.sup.5 is hydrogen.

3. A method according to claim 2 wherein component (b) is an epoxide.

4. A composition comprising a quaternary ammonium compound of formula (I): ##STR00018## wherein R.sup.0, R.sup.1, R.sup.2 and R.sup.3 is each independently an optionally substituted hydrocarbyl group, X is a linking group, R.sup.4 is an optionally substituted alkylene group, R.sup.5 is hydrogen or an optionally substituted alkyl, alkenyl or aryl group, and n is 0 or a positive integer, provided that n is not 0 when R.sup.5 is hydrogen.

5. A composition according to claim 4 wherein the composition is an additive composition for a fuel or lubricating oil.

6. A composition according to claim 4 wherein the composition is a fuel composition, preferably a diesel fuel composition.

7. Use of a quaternary ammonium compound of formula (I): ##STR00019## wherein R.sup.0, R.sup.1, R.sup.2 and R.sup.3 is each individually an optionally substituted alkyl, alkenyl or aryl group, X is a linking group, R.sup.4 is an optionally substituted alkylene group, R.sup.5 is hydrogen or an optionally substituted alkyl, alkenyl or aryl group, and n is 0 or a positive integer, provided that n is not 0 when R.sup.5 is hydrogen as an additive in a fuel or lubricant composition.

8. A method of improving the performance of an engine, the method comprising combusting in the engine a fuel composition comprising as an additive a quaternary ammonium compound of formula (I): ##STR00020## wherein R.sup.0, R.sup.1, R.sup.2 and R.sup.3 is each independently an optionally substituted hydrocarbyl group, X is a linking group, R.sup.4 is an optionally substituted alkylene group, R.sup.5 is hydrogen or an optionally substituted alkyl, alkenyl or aryl group, and n is 0 or a positive integer, provided that n is not 0 when R.sup.5 is hydrogen.

9. A salt, composition, method or use according to any preceding claim wherein HOOCXCOO(R.sup.4O).sub.nR.sup.5 is derived from a hydrocarbyl substituted succinic acid or a hydrocarbyl substituted succinic anhydride.

10. A salt, composition, method or use according to any preceding claim wherein each R.sup.4 is ethylene or propylene, preferably CH.sub.2CH.sub.2 or CH(CH.sub.3)CH.sub.2, more preferably CH(CH.sub.3)CH.sub.2.

11. A salt, composition, method or use according to any preceding claim wherein R.sup.5 is hydrogen and n is at least 1.

12. A salt, composition, method or use according to any of claims 1 to 10 wherein R.sup.5 is an optionally substituted alkyl group having 4 to 40 carbon atoms and n is from 0 to 40.

13. A salt, composition, method or use according to any preceding claim wherein each of R.sup.1 and R.sup.2 is independently an optionally substituted alkyl group having from 1 to 12 carbon atoms.

14. A salt, composition, method or use according to any preceding claim wherein R.sup.3 is an alkyl or hydroxyalkyl group having 1 to 10 carbon atoms.

15. A salt, composition, method or use according to any of claims 1 to 13 wherein R.sup.3 is selected from: (1) a polyisobutenyl group having a molecular weight of from 100 to 5000, preferably from 450 to 2500; (2) an optionally substituted alkylene phenol moiety of formula (A) or (B) ##STR00021## wherein n is 0 to 4, preferably 1, R.sup.x is an optionally substituted hydrocarbyl group, R.sup.y is an optionally substituted alkyl, alkenyl or aryl group; and L is a linking group; and (3) a succinimide moiety of formula: ##STR00022## wherein R.sup.z is an optionally substituted hydrocarbyl group and L is a linking group.

16. A salt, composition, method or use according to any preceding claim wherein R.sup.0 as is a group of formula: ##STR00023## wherein each of R.sup.9, R.sup.10, R.sup.11, R.sup.12 is independently selected from hydrogen or an optionally substituted alkyl, alkenyl or aryl group.

17. A salt, composition, method or use according to any preceding claim wherein X is an optionally substituted alkylene or arylene group.

18. A salt, composition, method or use according to any of claim 1 to 14, 16 or 17 the quaternary ammonium compound is the reaction product of: (a) a tertiary amine of formula R.sup.1R.sup.2R.sup.3N wherein each of, R.sup.1, R.sup.2 and R.sup.3 is independently an optionally substituted alkyl group having 1 to 12 carbon atoms; (b) an epoxide selected from styrene oxide, ethylene oxide, propylene oxide, butylene oxide, epoxyhexane, octene oxide, stilbene oxide, 2-ethylhexyl glycidyl ether, 1,2-epoxydodecane and other alkyl and alkenyl epoxides having 2 to 50 carbon atoms; and (c) a compound of formula HOOCXCOO(R.sup.4O).sub.nR.sup.5 wherein X is CH.sub.2CHR or CHRCH.sub.2 wherein R is an optionally substituted hydrocarbyl group; and n is more than 1, R.sup.4 is an ethylene or propylene group and R.sup.5 is hydrogen; or n is 0 or and R.sup.5 is a C.sub.1 to C.sub.20 alkyl group.

19. A salt, composition, method or use according to any of claims 1 to 14 or 16 to 18 wherein the quaternary ammonium compound is the reaction product of: (a) a tertiary amine of formula R.sup.1R.sup.2R.sup.3N wherein each of, R.sup.1, R.sup.2 and R.sup.3 is independently an alkyl or hydroxyalkyl group having 1 to 6 carbon atoms; (b) an epoxide selected from propylene oxide, butylene oxide and 2-ethylhexyl glycidyl ether; and (c) a compound of formula HOOCXCOO(R.sup.4O).sub.nR.sup.5 which is the reaction product of a succinic acid or anhydride having a C.sub.20 to C.sub.24 alkyl or alkenyl substituent and an alcohol selected from polypropylene glycol having a number average molecular weight of 300 to 800, 2-ethylhexanol and butanol.

20. A composition, method or use according to of claims 4 to 19 wherein the composition is a diesel fuel composition.

21. A composition, method or use according to claim 20 wherein the diesel fuel composition comprises one or more further detergents selected from: (i) a quaternary ammonium salt additive; (ii) the product of a Mannich reaction between an aldehyde, an amine and an optionally substituted phenol; (iii) the reaction product of a carboxylic acid-derived acylating agent and an amine; (iv) the reaction product of a carboxylic acid-derived acylating agent and hydrazine; (v) a salt formed by the reaction of a carboxylic acid with di-n-butylamine or tri-n-butylamine; (vi) the reaction product of a hydrocarbyl-substituted dicarboxylic acid or anhydride and an amine compound or salt which product comprises at least one amino triazole group; and (vii) a substituted polyaromatic detergent additive.

22. A composition, method or use according to any of claims 4 to 21 wherein the diesel fuel composition comprises a mixture of two or more quarternary ammonium salt additives.

23. A method or use as defined in any of claims 7 to 22 wherein the additive is used as a detergent to combat deposits in a diesel fuel composition in a diesel engine.

24. A method or use according to any of claims 7 to 23 wherein which is carried out in a modern diesel engine having a high pressure fuel system.

25. A method or use according to any of claims 7 to 24 which achieves keep clean performance.

26. A method or use according to any of claims 7 to 25 which achieves clean up performance.

27. A method or use according to any of claims 19 to 26 wherein the deposits are injector deposits.

28. A method or use according to claim 27 wherein the deposits are internal diesel injector deposits.

29. A method or use according to any of claims 7 to 28 which achieves an improvement in performance selected from one or more of: a reduction in power loss of the engine; a reduction in external diesel injector deposits; a reduction in internal diesel injector deposits; an improvement in fuel economy; a reduction in fuel filter deposits; a reduction in emissions; and an increase in maintenance intervals.

30. A method or use according to claim 29 which provides an improvement in performance in modern diesel engines having a high pressure fuel system and provides an improvement in performance in traditional diesel engines.

31. Use according to any of claims 3 to 30 which provides one or more further benefits selected from lubricity benefits, corrosion inhibition and cold flow improvement.

32. A composition according to any of claims 1 or 4 to 22 which further comprises one or more further additives selected from lubricity improvers, corrosion inhibitors and cold flow improvers.

33. Use of an ester additive as defined in any preceding claim to reduce the treat rate of one or more further additives selected from lubricity improvers, corrosion inhibitors and cold flow improvers whilst maintaining performance.

Description

EXAMPLE 1

[0510] Additive A1, a quaternary ammonium salt additive of the invention was prepared as follows:

(a) A mixture of alkenes having 20 to 24 carbon atoms was heated with 1.2 molar equivalents of maleic anhydride. On completion of the reaction excess maleic anhydride was removed by distillation. The anhydride value of the substituted succinic anhydride product was measured as 2.591 mmolg.sup.1.

[0511] This product was then heated with one molar equivalent of polypropylene glycol having a number average molecular weight of 425, and the reaction was monitored by FTIR to provide the half ester/half acid product.

(b) 1 molar equivalent of diethyl ethanolamine was reacted with 1.5 molar equivalents of butylene oxide and 6 molar equivalents of water at 60 C. in toluene for 10 hours in the presence of the half ester/half acid provided in the step (a) to form a quaternary ammonium compound. Volatiles were removed in vacuo.

[0512] Compounds A2 to A21 detailed in table 1 were prepared by an analogous method.

TABLE-US-00001 TABLE 1 Compound R H(OR.sup.4)n-OR.sup.5 Amine Epoxide A1 C20-24 polypropylene Diethyl ethanolamine Butylene oxide glycol Mn425 A2 C20-24 polypropylene Dimethyl ethanolamine Butylene oxide glycol Mn425 A3 C20-24 polypropylene Triethylamine Butylene oxide glycol Mn425 A4 C20-24 polypropylene Tributylamine Butylene oxide glycol Mn425 A5 C20-24 tripropylene glycol Dimethyl ethanolamine Butylene oxide A6 C20-24 tripropylene glycol Diethyl ethanolamine Butylene oxide A7 C20-24 tripropylene glycol Triethylamine Butylene oxide A8 C20-24 tripropylene glycol Tributylamine Butylene oxide A9 C20-24 triethyleneglycol Dimethyl ethanolamine Butylene oxide A10 C20-24 triethyleneglycol Diethyl ethanolamine Butylene oxide A11 C20-24 triethyleneglycol Triethylamine Butylene oxide A12 C20-24 triethyleneglycol Tributylamine Butylene oxide A13 C20-24 polypropylene Dimethyl ethanolamine Butylene oxide glycol Mn725 A14 C20-24 polypropylene Diethyl ethanolamine Butylene oxide glycol Mn725 A15 C20-24 polypropylene Triethylamine Butylene oxide glycol Mn725 A16 C20-24 polypropylene Tributylamine Butylene oxide glycol Mn725 A17 C20-24 Tetraethyleneglycol Dimethyl ethanolamine Butylene oxide A18 C20-24 Tetraethyleneglycol Diethyl ethanolamine Butylene oxide A19 C20-24 tetraethyleneglycol Triethylamine Butylene oxide A20 C20-24 tetraethyleneglycol Tributylamine Butylene oxide A21 C20-24 polyethyleneglycol Dimethyl ethanolamine Butylene oxide Mn400 A22 C20-24 2-Ethylhexanol N,N-diethyl ethanolamine Butylene oxide A23 C20-24 Butanol N,N-diethyl ethanolamine Butylene oxide A24 C20-24 Poly(ethylene 2-[2-(Dimethylamino)ethoxy] 1,2- glycol) Mn400 ethanol epoxydodecane A25 C20-24 Poly(ethylene N,N-dimethyl Benzylamine 2-Ethylhexyl glycol) Mn400 Glycidyl Ether A26 C20-24 Poly(ethylene N,N-dimethyl ethanolamine 1,2- glycol) Mn400 epoxydodecane A27 C20-24 Poly(ethylene N,N-dimethyl ethanolamine Styrene Oxide glycol) Mn400 A28 C20-24 Poly(ethylene N,N-Dimethyl 2-Ethylhexyl glycol) Mn400 octadecylamine Glycidyl Ether A29 C20-24 Poly(ethylene N,N-Dimethyl Butylene oxide glycol) Mn400 octadecylamine A30 C20-24 Poly(ethylene N,N-Dimethyl 1,2- glycol) Mn400 octadecylamine epoxydodecane A31 C20-24 Poly(ethylene N,N-Dimethyl Styrene Oxide glycol) Mn400 octadecylamine A32 C20-24 Poly(propylene N,N-dimethyl Benzylamine 2-Ethylhexyl glycol) Mn425 Glycidyl Ether A33 C20-24 Poly(propylene N,N-dimethyl Benzylamine Butylene oxide glycol) Mn425 A34 C20-24 Poly(propylene N,N-dimethyl Benzylamine Styrene Oxide glycol) Mn425 A35 C20-24 Poly(propylene N,N-dimethyl ethanolamine 1,2- glycol) Mn425 epoxydodecane A36 C20-24 Poly(propylene N,N-Dimethyl 2-Ethylhexyl glycol) Mn425 octadecylamine Glycidyl Ether A37 C20-24 Poly(propylene N,N-Dimethyl Butylene oxide glycol) Mn425 octadecylamine A38 C20-24 Poly(propylene N,N-Dimethyl Styrene Oxide glycol) Mn425 octadecylamine A39 C20-24 Tetradecanol N,N-diethyl ethanolamine Butylene oxide A40 C20-24 Tri(propylene 2-[2-(Dimethylamino)ethoxy] 2-Ethylhexyl glycol) ethanol Glycidyl Ether A41 C20-24 Tri(propylene 2-[2-(Dimethylamino)ethoxy] 1,2- glycol) ethanol epoxydodecane A42 C20-24 Tri(propylene 2-[2-(Dimethylamino)ethoxy] Styrene Oxide glycol) ethanol A43 C20-24 Tri(propylene N,N-dimethyl Benzylamine 2-Ethylhexyl glycol) Glycidyl Ether A44 C20-24 Tri(propylene N,N-dimethyl Benzylamine Butylene oxide glycol) A45 C20-24 Tri(propylene N,N-dimethyl Benzylamine 1,2- glycol) epoxydodecane A46 C20-24 Tri(propylene N,N-dimethyl Benzylamine Styrene Oxide glycol) A47 C20-24 Tri(propylene N,N-dimethyl ethanolamine 1,2- glycol) epoxydodecane A48 C20-24 Tri(propylene N,N-Dimethyl 2-Ethylhexyl glycol) octadecylamine Glycidyl Ether A49 C20-24 Tri(propylene N,N-Dimethyl Butylene oxide glycol) octadecylamine A50 C20-24 Tri(propylene N,N-Dimethyl 1,2- glycol) octadecylamine epoxydodecane A51 C20-24 Tri(propylene N,N-Dimethyl Styrene Oxide glycol) octadecylamine A52 1000PIB Tri(propylene N,N-dimethyl ethanolamine 1,2- glycol) epoxydodecane

EXAMPLE 2

[0513] Diesel fuel compositions were prepared by dosing additives to aliquots all drawn from a common batch of RF06 base fuel.

[0514] The compositions were tested in a screening test which correlates with performance at combatting IDIDs as measured in the DW10C test.

[0515] In this test a fuel composition is tested using a Jet Fuel Thermal Oxidation Test equipment. In this modified test 800 ml of fuel is flowed over a heated tube at pressures of approximately 540 psi. The test duration is 2.5 hours. At the end of the test the amount of deposit obtained on the tube is compared to a reference value.

[0516] The value shown in table 2 is the percentage reduction in deposit thickness compared to base fuel.

TABLE-US-00002 TABLE 2 ppm Average thickness Compound active (% reduction) A1 (inventive) 120 95 A3 (inventive) 120 97 A4 (inventive) 120 95 A6 (inventive) 120 84 A7 (inventive) 120 98 A8 (inventive) 120 97 A10 (inventive) 120 92 A11 (inventive) 120 92 A12 (inventive) 120 91 A14 (inventive) 120 99 A15 (inventive) 120 91 A16 (inventive) 120 98 A19 (inventive) 120 91 A20 (inventive) 120 91 A22 (inventive) 120 81 A23 (inventive) 120 91 A24 (inventive) 120 98 A25 (inventive) 120 80 A26 (inventive) 120 98 A27 (inventive) 120 81 A28 (inventive) 120 79 A29 (inventive) 120 90 A30 (inventive) 120 97 A31 (inventive) 120 100 A32 (inventive) 120 95 A33 (inventive) 120 92 A34 (inventive) 120 90 A35 (inventive) 120 94 A36 (inventive) 120 91 A37 (inventive) 120 99 A38 (inventive) 120 96 A40 (inventive) 120 85 A41 (inventive) 120 82 A42 (inventive) 120 85 A43 (inventive) 120 90 A44 (inventive) 120 97 A45 (inventive) 120 99 A46 (inventive) 120 78 A47 (inventive) 120 97 A48 (inventive) 120 87 A49 (inventive) 120 91 A50 (inventive) 120 99 A51 (inventive) 120 78 C1 (comparative) 120 0 C2 (comparative) 120 2

[0517] Comparative additive C1 is dodecenyl substituted succinic acid.

[0518] Comparative additive C2 is a polyisobutenyl (FIB) substituted succinic acid where the PIB has a number average molecular weight of 1000.

[0519] Table 3 below shows the specification for RF06 base fuel.

TABLE-US-00003 TABLE 3 Limits Property Units Min Max Method Cetane Number 52.0 54.0 EN ISO 5165 Density at 15 C. kg/m.sup.3 833 837 EN ISO 3675 Distillation 50% v/v Point C. 245 95% v/v Point C. 345 350 FBP C. 370 Flash Point C. 55 EN 22719 Cold Filter Plugging C. 5 EN 116 Point Viscosity at 40 C. mm.sup.2/sec 2.3 3.3 EN ISO 3104 Polycyclic Aromatic % m/m 3.0 6.0 IP 391 Hydrocarbons Sulphur Content mg/kg 10 ASTM D 5453 Copper Corrosion 1 EN ISO 2160 Conradson Carbon % m/m 0.2 EN ISO 10370 Residue on 10% Dist. Residue Ash Content % m/m 0.01 EN ISO 6245 Water Content % m/m 0.02 EN ISO 12937 Neutralisation (Strong mg KOH/g 0.02 ASTM D 974 Acid) Number Oxidation Stability mg/mL 0.025 EN ISO 12205 HFRR (WSD1, 4) m 400 CEC F-06-A-96 Fatty Acid Methyl prohibited Ester

EXAMPLE 3

[0520] The performance of fuel compositions of example 2 in modern diesel engines having a high pressure fuel system may be tested according to the CECF-98-08 DW 10 method. This is referred to herein as the DW10B test.

[0521] The engine of the injector fouling test is the PSA DW10BTED4. In summary, the engine characteristics are:

Design: Four cylinders in line, overhead camshaft, turbocharged with EGR

Capacity: 1998 cm.SUP.3

[0522] Combustion chamber: Four valves, bowl in piston, wall guided direct injection

Power: 100 kW at 4000 rpm

Torque: 320 Nm at 2000 rpm

[0523] Injection system: Common rail with piezo electronically controlled 6-hole injectors.
Max. pressure: 1600 bar (1.610.sup.8 Pa). Proprietary design by SIEMENS VDO
Emissions control: Conforms with Euro IV limit values when combined with exhaust gas post-treatment system (DPF)

[0524] This engine was chosen as a design representative of the modern European high-speed direct injection diesel engine capable of conforming to present and future European emissions requirements. The common rail injection system uses a highly efficient nozzle design with rounded inlet edges and conical spray holes for optimal hydraulic flow. This type of nozzle, when combined with high fuel pressure has allowed advances to be achieved in combustion efficiency, reduced noise and reduced fuel consumption, but are sensitive to influences that can disturb the fuel flow, such as deposit formation in the spray holes. The presence of these deposits causes a significant loss of engine power and increased raw emissions.

[0525] The test is run with a future injector design representative of anticipated Euro V injector technology.

[0526] It is considered necessary to establish a reliable baseline of injector condition before beginning fouling tests, so a sixteen hour running-in schedule for the test injectors is specified, using non-fouling reference fuel.

[0527] Full details of the CEC F-98-08 test method can be obtained from the CEC. The coking cycle is summarised below.

1. A warm up cycle (12 minutes) according to the following regime:

TABLE-US-00004 Duration Engine Speed Torque Step (minutes) (rpm) (Nm) 1 2 idle <5 2 3 2000 50 3 4 3500 75 4 3 4000 100
2. 8 hrs of engine operation consisting of 8 repeats of the following cycle

TABLE-US-00005 Duration Engine Speed Load Torque Boost Air After IC Step (minutes) (rpm) (%) (Nm) ( C.) 1 2 1750 (20) 62 45 2 7 3000 (60) 173 50 3 2 1750 (20) 62 45 4 7 3500 (80) 212 50 5 2 1750 (20) 62 45 6 10 4000 100 * 50 7 2 1250 (10) 20 43 8 7 3000 100 * 50 9 2 1250 (10) 20 43 10 10 2000 100 * 50 11 2 1250 (10) 20 43 12 7 4000 100 * 50 * for expected range see CEC method CEC-F-98-08
3. Cool down to idle in 60 seconds and idle for 10 seconds
4. 4 hrs soak period

[0528] The standard CEC F-98-08 test method consists of 32 hours engine operation corresponding to 4 repeats of steps 1-3 above, and 3 repeats of step 4. ie 56 hours total test time excluding warm ups and cool downs.

EXAMPLE 4

[0529] The ability of additives of the invention to remove Internal Diesel Injector Deposits (IDIDs) may be measured according to he test method CEC F-110-16, available from the Co-ordinating European Council. The test uses the PSA DW10C engine.

[0530] The engine characteristics as follows:

TABLE-US-00006 Design: Four cylinders in line, overhead camshaft, variable geometry turbocharger with EGR Capacity: 1997 cm.sup.3 Combustion Four valves, bowl in piston, direct injection chamber: Power: 120 kW @ 3750 rpm Torque: 340 Nm @ 2000 rpm Injection Common rail with solenoid type injectors system: Delphi Injection System Emissions Conforms to Euro V limit values when combined with control: exhaust gas post-treatment system.

[0531] The test fuel (RF06) is dosed with 0.5 mg/kg Na in the form of Sodium Naphthenate+10 mg/kg Dodecyl Succinic Acid (DDSA).

[0532] The test procedure consists of main run cycles followed by soak periods, before cold starts are carried out.

[0533] The main running cycle consist of two speed and load set points, repeated for 6 hrs, as seen below.

TABLE-US-00007 Speed Torque Duration Step (rpm) (N .Math. m) (s) 1 3750 280 1470 1 - Ramp .fwdarw. 2 30 2 1000 10 270 2 - Ramp .fwdarw. 1 30

[0534] The ramp times of 30 seconds are included in the duration of each step.

[0535] During the main run, parameters including, Throttle pedal position, ECU fault codes, Injector balance coefficient and Engine stalls are observed and recorded.

[0536] The engine is then left to soak at ambient temperature for 8 hrs.

[0537] After the soak period the engine is re-started. The starter is operated for 5 seconds; if the engine fails to start the engine is left for 60 seconds before a further attempt. A maximum of 5 attempts are allowed.

[0538] If the engine starts the engine is allowed to idle for 5 minutes. Individual exhaust temperatures are monitored and the maximum Temperature Delta is recorded. An increased variation in Cylinder-to-Cylinder exhaust temperatures is a good indication that injectors are suffering from IDID. Causing them to either open slowly or stay open to long.

[0539] An example below of all exhaust temperatures with <30 C. deviation, indicating no sticking caused by IDID.

[0540] The complete test comprises of 6 Cold Starts, although the Zero hour Cold Start does not form part of the Merit Rating and 5 6 hr Main run cycles, giving a total of 30 hrs engine running time.

[0541] The recorded data is inputted into the Merit Rating Chart. This allows a Rating to be produced for the test. Maximum rating of 10 shows no issues with the running or operability of the engine for the duration of the test.

[0542] An example below:

TABLE-US-00008 Cold start Starting Exhaust temperature consistency Number Exhaust of Temperature Attempts Max Cyl. Cold Start Maximum (1 = Maximum Deviation Start Y/N Merits first start) Deduction Merits Merits ( C.) Deduction Merits #0 not rated #1 Y 5 1 0 5 5 21.8 0 5 #2 Y 5 1 0 5 5 18.1 0 5 #3 Y 5 1 0 5 5 15.5 0 5 #4 Y 5 1 0 5 5 20.2 0 5 #5 Y 5 1 0 5 5 22.6 0 5 Total 25 25 merits Main run Operabiity Max Pedal Max Number Position Inject. of ECU at 1000 Balancing Main Maximum Fault Deduc- Stall Deduct- rpm/10 Deduc- Coeff. Deduc- run Merits resets tion (Y/N) ion N.m (%) tion (rpm) tion Merits #1 5 0 0 N 0 15.4 0 15 0 5 #2 5 0 0 N 0 13.5 0 15 0 5 #3 5 0 0 N 0 13.6 0 16 0 5 #4 5 0 0 N 0 13.8 0 15 0 5 #5 5 0 0 N 0 14.5 0 15 0 5 25 Global Rating-Summary (Merit/10) 10

EXAMPLE 5

[0543] The effectiveness of the additives of the invention in older traditional diesel engine types was assessed using a standard industry testCEC test method No. CEC F-23-A-01.

[0544] This test measures injector nozzle coking using a Peugeot XUD9 A/L Engine and provides a means of discriminating between fuels of different injector nozzle coking propensity. Nozzle coking is the result of carbon deposits forming between the injector needle and the needle seat. Deposition of the carbon deposit is due to exposure of the injector needle and seat to combustion gases, potentially causing undesirable variations in engine performance.

[0545] The Peugeot XUD9 A/L engine is a 4 cylinder indirect injection Diesel engine of 1.9 litre swept volume, obtained from Peugeot Citroen Motors specifically for the CEC PF023 method.

[0546] The test engine is fitted with cleaned injectors utilising unflatted injector needles. The airflow at various needle lift positions have been measured on a flow rig prior to test. The engine is operated for a period of 10 hours under cyclic conditions.

TABLE-US-00009 Time Speed Torque Stage (secs) (rpm) (Nm) 1 30 1200 30 10 2 2 60 3000 30 50 2 3 60 1300 30 35 2 4 120 1850 30 50 2

[0547] The propensity of the fuel to promote deposit formation on the fuel injectors is determined by measuring the injector nozzle airflow again at the end of test, and comparing these values to those before test. The results are expressed in terms of percentage airflow reduction at various needle lift positions for all nozzles. The average value of the airflow reduction at 0.1 mm needle lift of all four nozzles is deemed the level of injector coking for a given fuel.

[0548] The results of this test using the specified additive combinations of the invention are shown in table 3. In each case the specified amount of active additive was added to an RF06 base fuel meeting the specification given in table 2 (example 5) above.