GB2259522A - Compositions for control of induction system deposits - Google Patents

Abstract

Distillate fuels and additive concentrates comprising (a) a detergent/dispersant prepared by reacting (i) a polyamine, eg triethylene tetramine or a combination of ethylene polyamines, which approximate triethylene tetramine, with (ii) at least one acyclic hydrocarbyl-substituted succinic acylating agent characterized by having an acid number in the range of 0.7 to 1.1. and by having a substituent containing an average of 50 to 100 carbon atoms; and (b) a mineral oil, eg napthenic or asphaltic oils, having a viscosity index of less than about 90 and a volatility of less than 50% as determined by a method disclosed, are particularly effective in reducing the amount of induction system deposits formed in an engine under normal service conditions. The detergent/dispersant contains in its molecular structure in chemically combined form an average of from 1.5 to 2.2 moles of (ii) per mole of (i).

Description

COMPOSITIONS FOR CONTROL OF INDUCTION SYSTEM DEPOSITS This invention relates to controlling fuel induction system deposits in internal combustion engines. More particularly this invention relates to detergent/dispersant compositions and to gasoline type fuels and fuels mixtures for internal combustion engines, said fuels and mixtures capable of reducing or at least minimizing the amount of intake valve deposits formed during engine operation.

A problem frequently encountered in the operation of internal combustion engines is the formation of undesirable amounts of engine deposits, such as fuel injector and intake valve deposits, which form during engine operation.

An object of this invention is to provide compositions capable of reducing the severity of this problem. Another object is to provide compositions which also reduce deposits which are already present due to prior operation with fuels compositions which have formed such deposits.

As the emphasis has shifted to providing fuels and fuel mixtures which are more environmentally "friendly", and as more vehicles are being equipped with fuel injectors to increase the efficiency and further reduce emissions from internal combustion engines, a need has developed for fuels and fuel mixtures which reduce and/or eliminate the amount of deposits which accumulate on fuel injectors and intake valves. To reduce the amount of deposits on the fuel injectors, detergent additives designed for this purpose have been added to fuel compositions. While these detergents provide a significant reduction in the deposits which heretofore have hindered the operation of fuel injected internal combustion engines, such formulations may not provide the most desirable detergent effect for inhibiting and/or cleaning deposits on other internal engine parts, e.g., intake valves.There is a need therefore for detergents which not only keep fuel injectors clean but which effectively control deposits on intake valves as well as other engine parts of internal combustion engines.

This invention provides a fuel additive concentrate comprising, as a detergent/dispersant, (a) the reaction product of (i) polvamine and (ii) at least one acyclic hydrocarbyl-substituted succinic acylating agent; and (b) a mineral oil having a viscosity index of less than about 90 and a volatility of less than 50% as determined by a test method described herein.

In one of its forms, this invention provides a major amount of hydrocarbons in the gasoline boiling range or hydrocarbon/oxygenate mixtures, or oxygenates containing a minor, but effective amount, of (a) a fuel additive comprising the reaction product of (i) polyamine and (ii) at least one acyclic hydrocarbyl-substituted succinic acylating agent; and (b) mineral oil having a viscosity index of less than about 90, and a volatility of less than 50% as determined by a test method described herein and optionally, but preferably, (c) an antioxidant, or (d) a demulsifier, or (e) an aromatic hydrocarbon solvent, or (f) a corrosion inhibitor, or any combination of any two or three or all four of components (c), (d), (e) and (f). Other performance additives such as combustion improvers and octane improvers, may also be present.

Another embodiment of this invention is a method for controlling deposits which form on internal parts of an internal combustion engine which comprises providing for use as a fuel composition (a) a major amount of hydrocarbons in the gasoline boiling range or hydrocarbon/oxygenate mixtures, or oxygenates and (b) a minor but effective amount of a deposit control mixture comprising (i) the reaction product of polyamine and at least one acyclic hydrocarbyl-substituted succinic acylating agent, and (ii) a mineral oil having a viscosity index of less than about 90 and a volatility of less than SONG as determined by a test method described herein whereby deposits which may form on internal parts of the internal combustion engine during operation are effectively controlled.

These and other embodiments of this invention will be apparent from the ensuing description and appended claims.

Detergent/dispersant. As noted above, the fuel additive concentrate of this invention comprises (a) as a detergent/dispersant, the reaction product of (i) polyamine and (ii) at least one acvclic hydrocarQvl-substituted succinic acylating agent; and (b) a mineral oil having a viscosity index of less than about 90 and a volatility of less than 50% as determined by the test method described herein.

The polyamine reactant may be one or more alkylene polyamine(s), which polyamines may be linear, branched, or cyclic; or a mixture of linear, branched and/or cyclic polyamines and wherein each alkylene group contains from 1 to 10 carbon atoms. A preferred polyamine is a polyamine containing from 2 to 10 nitrogen atoms per molecule or a mixture of polyamines containing an average of from 2 to 10 nitrogen atoms per molecule. A particularly preferred polyamine is a polyamine or mixture of polyamines having from 3 to 7 nitrogen atoms with triethylene tetramine or a combination of ethylene poly-amines which approximate triethylene tetramine being the most preferred. In selecting an appropriate polyamine, consideration should be given to the compatibility of the resulting detergent/ dispersant with the fuel mixture with which it is mixed.

Ordinarily the most highly preferred polyamine, triethylene tetramine, will comprise a commercially available mixture having the general overall composition approximating that of triethylene tetramine but which can contain minor amounts of branched-chain and cyclic species as well as some linear polyethylene polyamines such as diethylene triamine and tetraethylene pentamine.

For best results, such mixtures should contain at least 50C/i; and preferably at least 70% by weight of the linear polyethylene polyamines enriched in triethylene tetramine.

The acylating agent which is reacted with the polyamine is an acyclic hydrocarbyl-substituted succinic acylating agent in which the substituent contains an average of 50 to 100 (preferably 64 to 80) carbon atoms. In order to accomplish the objectives of this invention, it is important that the acyclic hydrocarbyl substituted succinic acylating agent have an acid number in the range of 0.7 to 1.1 (preferably in the range of 0.8 to I .0, and most preferably 0.9).

To achieve the objectives of this invention, the molar ratio of acylating agent to polyamine in the reaction product of (i) and (ii) is desirably greater than 1:1. Preferably the molar ratio of acylating agent to polyamine in the reaction product is in the range of 1.5 : 1 to 2.2 : 1, more preferably from 1.7 : 1 to 1.9 1, and most preferably 1.8 1.

The acid number of the acyclic hycirocarbyl substituted succinic acylating agent is determined in the customary way -- i.e., bv titration -- and is reported in terms of mg of KOH per gram of product. It is to be noted that this determination is made on the overall acylating agent with any unreacted olefin polymer (e.g., polyisobutene) present.

The acyclic hydrocarbyl substituent of the acylating agent is preferably an alkyl or alkenyl group having the requisite number of carbon atoms as specified above. Alkenyl substituents derived from poly-a-olefin homopolymers or copolymers of appropriate molecular weight (e.g., propene homopolymers, butene homopolymers, Q and C4 a-olefin copolymers, and the like) are suitable. Most preferably, the substituent is a polyisobutenyl group formed from polyisobutene having a number average molecular weight (as determined by gel permeation chromatography) in the range of 700 to 1200, preferably 900 to 1100, most preferably 940 to 1000.

Acyclic hydrocarbyl-substituted succinic acid acylating agents and methods for their preparation and use in the formation of succinimide are well known to those skilled in the art and are extensively reported in the patent literature. See for example the following U. S. Patents.

3,018,247 3,231,587 3,399,141 3,018,250 3,272,746 3,401,118 3,018,291 3,287,271 3,513,093 3,172,892 3*311,558 3,576,743 3,184,474 3,331,776 3,578,422 3,185,704 3,341,542 3,658,494 3,194,812 3,346,354 3,658,495 3,194,814 3,347,645 3,912,764 3,202,678 3,361,673 4,110,349 3,215,707 3,373,111 4,234,435 3,219,666 3,381,()99 When utilizing the general procedures such as described in these patents, the important considerations insofar as the present invention is concerned, are to insure that the hydrocarbyl substituent of the acylating agent contain the requisite number of carbon atoms, that the acylating agent have the requisite acid number, that the acylating agent be reacted with the requisite polyethylene polyamine, and that the reactants be employed in proportions such that the resultant succinimide contains the requisite proportions of the chemically combined reactants, all as speci fied herein. When utilizing this combination of features, detergent/dispersants are formed which possess exceptional effectiveness in controlling or reducing the amount of induction system deposits formed during engine operation.

As pointed out in the above listed patents, the acyclic hydrocarbylsubstituted succinic acylating agents include the hydrocarbyl-substituted succinic acids, the hydrocarbyl-substituted succinic anhydrides, the hydrocarbyl-substituted succinic acid halides (especially the acid fluorides and acid chlorides), and the esters of the hydrocarbyl-substituted succinic acids and lower alcohols (e.g., those containing up to 7 carbon atoms), that is, hydrocarbyl-substituted compounds which can function as carboxylic acylating agents. Of these compounds, the hydrocarbylsubstituted succinic acids and the hydrocarbyl-substituted succinic anhydrides and mixtures of such acids and anhydrides are generally preferred, the hydrocarbylsubstituted succinic anhydrides being particularly preferred.

The acylating agent used in producing the detergent/dispersants of this invention is preferably made by reacting a polyolefin of appropriate molecular weight (with or without chlorine) with maleic anhydride. However, similar carboxylic reactants can be employed such as maleic acid, fumaric acid, malic acid, tartaric acid, itaconic acid, itaconic anhydride, citraconic acid, citraconic anhydride, mesaconic acid, ethyl-maleic anhydride, dimethvlmaleic anhydride, ethylmaleic acid, dimethylmaleic acid, hexvlmaleic acid, and the like, including the corresponding acid halides and lower aliphatic esters.

The reaction between components (i) and (ii) is generally conducted at temperatures of 80"C to 900on, more preferably 140 C to 180"C, such that a succinimide is formed. These reactions may be conducted in the presence or absence of an ancillary diluent or liquid reaction medium, such as a mineral lubricating oil solvent. Suitable solvent oils include natural and synthetic base oils having a volatility of less than 50G as determined by the test method described herein. The natural oils are typically mineral oils.Suitable synthetic diluents include polyesters, hydrogenated or unhydrouenated poly-a-olefins (PAO) such as hydrogenated or unhvdrogenated l-decene oligomer, and the like. Blends of mineral oil and synthetic oils are also suitable for this purpose. In a particularly preferred embodiment, the reactions are eonducted in the substantial absence of an ancillary diluent oil so that the reaction product is essentially free of paraffinic mineral oils. By essentially free is meant that the reaction product contains less than about 1% by weight paraffinic mineral oil.

As used herein, the term succinimide is meant to encompass the completed reaction product from components (i) and (ii) and is intended to encompass compounds wherein the product may have amide, amidine, and/or salt linkages in addition to the imide linkage of the type that results from the reaction of a primary amino group and an anhydride moiety.

Mineral Oil. A key feature of this invention is the use of a mineral oil having a viscosity index of less than about 90 and a volatility of less than 50% as determined by the test method described herein as a diluent in the formation of the fuel additive concentrate or as a key component in blends of fuel mixtures and succinimide reaction product. The mineral oil more preferably has a volatility of less than 45%. It has been found that when particular succinimide and particular mineral oil components are admixed with gasoline in particular proportions, deposits on internal engine parts are effectively controlled. By "effectively controlled" is meant, that the formation of such deposits is significantly inhibited, and/or engines initially containing heavy deposits, exhibit a substantial reduction in deposits when operated in accordance with the method of this invention.

Mineral oils having suitable volatilities include naphthenic and asphaltic oils which are defined generally as those found along the Gulf Coast such as a Coastal Pale (commercially available from Exxon Co.). A typical Coastal Pale may contain 3-5 wt. % polar material, 20-35 wt.% aromatic hydrocarbons, and 50-75 wt.% saturated hydrocarbons and have a molecular weight in the range of from 300 to 600. Asphaltic oils are defined as containing high molecular weight (ca > 800) compounds with high polar functionality and little or no pure hydrocarbon type compounds. Principal polar functionalities generally present in such asphaltic oils include carboxylic acids, phenols, amides, carbazoles, and pyridine benzologs.

Typically, asphaltenes contain 40-50aRc by weight aromatic carbon and have molecular weights of several thousand. Asphaltic oils are generally found along the West Coast. Preferably the mineral oil has a viscosity at 100"F of less than 1600 SUS, more preferably less than 1500SUS, and most preferably between 800 and 1500 SUS at 1000 F. It is highly desirable that the mineral oil have a viscosity index of less than 90, more particularly, less than 70 and most preferably in the range of from 30 to 60. Suitable mineral oils may be selected from solvent extracted, hydrotreated, and non-hydrotreated mineral oils, however, the hydrotreated mineral oils are particularly desirable for use in the additive compositions of this invention.

The weight ratio of succinimide to the diluent oil in the mixtures of this invention is a particularly key feature of this invention. It has been discovered that a weight ratio of less than 1 part succinimide to 4 parts mineral oil achieves the purposes of this invention. Preferably the weight ratio of succinimide to mineral oil is in the range of from 1:1.5 to 1: 2.5 and most preferably, the weight ratio is from 1: 1.8two to 1: 2.2.

Antioxidant. Various compounds known for use as oxidation inhibitors can be utilized in the practice of this invention. These include phenolic antioxidants, amine anti-oxidants, sulfurized phenolic compounds, and organic phosphites, among others. For best results, the antioxidant should be composed predominantly or entirely of either (1) a hindered phenol antioxidant such as 2-tert-butylphenol, 2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol, 4-methyl-2,6-di-tert-butylphenol, 4,4'-methylenebis-(2,6-di-tert-butylphenol), and mixed methylene bridged polyalkyl phenols, or (2) an aromatic amine antioxidant such as the cycloalkvl-di-lower alkyl amines, and phenyienediamines, or a combination of one or more such phenolic antioxidants with one or more such amine antioxidants.

Demulsifier. A wide variety of demulsifiers are available for use in the practice of this invention, including, for example, organic sulfonates, polyoxyalkylene glycols, oxyalkylated phenolic resins, and like materials. Particularly pre-ferred are mixtures of alkylphenol or polyoxyalkylene glycols, and oxyalkylated alkylphenolic resins, such as are available commercially from Petrolite Corporation under the TOLAD trademark. One such proprietary product, identified as TOLAD 9308, is understood to be a mixture of these components dissolved in a solvent composed of heavy aromatic naphtha and isopropanol. This product has been found efficacious for use in the compositions of this invention. However, other known demulsifiers can be used such as TO LAD 286.

Corrosion Inhibitor. Here again, a variety of materials are available for use as corrosion inhibitors in the practice of this invention. Thus, use can be made of dimer and trimer acids, such as are produced from tall oil fatty acids, oleic acid, linoleic acid, or the like. Products of this type are currently available from various commercial sources, such as, for example, the dimer and trimer acids sold under the HYSTRENE trademark by the Humko Chemical Division of Witco Chemical Corporation and under the EMPOL trademark by Emery Chemicals.

Another useful type of corrosion inhibitor for use in the practice of this invention are the alkenyl succinic acid and alkenyl succinic anhydride corrosion inhibitors such as, for example, tetrapro-penylsuccinic acid, tetrapropenylsuccinic anhydride, tetradecenylsuccinic acid, tetradecenylsuccinic anhydride, hexadecenyl-succinic acid, hexadecenylsuccinic anhydride, and the like. Also useful are the half esters of alkenyl succinic acids having 8 to 24 carbon atoms in the alkenyl group with alcohols such as the polyglycols.Preferred materials are the succinic acids or derivatives thereof represented by the formula: o R 6----C-- - Fe F? --C - - C - ----0 OR 1 fe2 0 wherein each of R2, R3, R3 and R6 is, -independently, a hydrogen atom or a hydrocarbyl group containing l to 30 carbon atoms, and wherein each of Rl and R4 is, independently, a hydrogen atom, a hydrocarbyl group containing 1 to 30 carbon atoms, or an acyl group containing from 1 to 30 carbon atoms.

The groups Rl, R2, R3, R4, R5, and R6 when in the form of hydrocarbyl groups, can be, for example, alkyl, cycloalkyl or aromatic containing groups.

Preferably Rl, R2, R3, R4 and R5 are hydrogen or the same or different straightchain or branched-chain hydrocarbon radicals containing 1-20 carbon atoms. Most preferably, Rl, R2, R3, R4, and R5 are hydrogen atoms. R6 when in the form of a hydrocarbyl group is preferably a straight-chain or branched-chain saturated hydrocarbon radical.

Most preferred is an alkenyl succinic acid of the above formula wherein Rl, R2, R3, R4 and R5 are hydrogen and Rt is a tetrapropenyl group.

Aromatic Hvdrocarbon Solvent A wide variety of aromatic hydrocarbon solvents can be used with this invention such as benzene, and alkyl substituted benzene or mixtures thereof. Particularly useful are mixtures of o-, p-, and mxylenes, mesitylene, and higher boiling aromatics such as Aromatic 150 which is available from Chemtech. However, other mixtures of aromatic hydrocarbon solvents may also be used.

The relative proportions of the various ingredients used in the additive concentrates and fuels of this invention can he varied within reasonable limits.

However, for best results, these compositions should contain from 10 to 50 parts by weight (preferably from 20 to 35 parts by weight) of succinimide, up to 75 parts by weight (preferably from 50 to 65 parts by weight) of diluent oil, 0 to 5 parts by weight (preferably, from 1 to 3 parts by weight) of antioxidant, from 0 to 10 parts by weight (preferably, from 0.3 to 3 parts by weight) of demulsifier, from 0 to 75 parts by weight (preferably 5 to 25 parts by weight) of aromatic hydro-carbon solvent, and from 0 to 5 parts bv weight (preferably, from 0.025 to 1.0 parts by weight) of corrosion inhibitor per each one hundred parts by weight of fuel additive composition.

The above additive compositions of this invention are preferably employed in hydrocarbon mixtures in the gasoline boiling range or hydrocarbon/ oxygenate mixtures, or oxygenates, but are also suitable for use in middle distillate fuels, notably, diesel fuels and fuels for gas turbine engines. The nature of such fuels is so well known to those skilled in the art as to require no further comment.

By oxygenates is meant alkanols and ethers such as methanol, ethanol, propanol, methyl-tert-butyl ether, ethyl-tert-hutyl ether, tert-amvl-methyl ether and the like.

It will of course be understood that the base fuels may contain other commonly used ingredients such as cold Nta. ung aids, dyes, metal deactivators, octane improvers, cetane improvers, emission control additives. antioxidants, and the like.

When formulating the fuel compositions of this invention, the additives are employed in amounts sufficient to reduce or inhibit induction system deposits in an internal combustion engine. Generally speaking, the fuel additive comprising a succinimide and a mineral oil having a viscosity index of less than about 90 and a volatility of about less than 50% will be employed in unleaded gasoline in minor amounts such that the gasoline portion of the fuel is the major component. By minor amount is meant less than 1500 parts per million parts ofgasoline, preferably, less than 1200 parts per million parts of gasoline. A particularly preferred amount of additive is in the range of from 500 to 1000 parts per million parts of gasoline.

The other components which are preferably used in conjunction with the detergent/ dispersant and mineral oil can be blended into the fuel individually or in various subcombinations. However, it is definitely preferable to blend all of the components concurrently using an additive concentrate of this invention as this takes advantage of the mutual compatibility afforded by the combination of ingredients when in the form of an additive concentrate. It is to be understood that the additive concentrate of this invention may be further diluted to improve the handling of the additive composition in the field.

The following Examples in which all parts are by weight illustrate, but are not intended to limit, this invention.

Example l A fuel additive concentrate is prepared from the following ingredients: (a) 30 parts of a detergent/dispersant formed by reacting polyisobutenyl succinic anhydride having an acid number of 1.1 (made by reaction of maleic anhydride and polyisobutene having a number average molecular weight of 950) with a commercial mixture approximating triethylene tetramine, in a mole ratio of l.S : 1 respectively.

(b) 60 parts of naphthenic mineral oil of Witco Corporation 4053-Heavy.

(c) 2.8 parts of a tertiary butylated phenol antioxidant mixture containing a minimum of 75 percent of 2,6-di-tert-butylphenol, 10-15 percent of 2,4,6-tri-tert-butylphenol, and 15-10 percent of 2-tert-butylphenol.

(d) 1.5 parts of a demulsifier mixture composed of alkylaryl sulfonates, polyoxyalkylene glycols and oxyalkylated alkyiphenolic resins in alkylbenzenes (TOLAD 286).

(e) 6 parts of an aromatic solvent with a boiling range of 196-256C and a viscosity of 1.7 cSt at 25 C.

(f) 0.5 parts of tetrapropenyl succinic acid, supplied as a 50% solution in light mineral oil.

This concentrate is blended with gasoline at concentrations of 150 pounds per thousand barrels (PTB).

Example 2 Example 1 is repeated using each of the components set forth therein except that 180 pounds per thousand barrels (PTB) of the concentrate additive is formulated with gasoline.

Example 3 Example 1 is repeated using each of the components set forth therein except that 225 pounds per thousand barrels (PTB) of the concentrate additive is used in the gasoline mixture.

The effectiveness of the compositions of this invention in reducing induction system deposits was demonstrated in a series of standard engine tests using the test gasoline formulation as in Examples 1. 2 and 3.

Example 4 In one set of tests -- the Briggs and Stratton engine test -- the formulation of Example 1 was compared to an untreated gasoline. The test utilized a Briggs & Stratton 3 Hp engine with SAE l()W-40 oil. The length of the test was 150 hours. After breaking the engine in at Varying speeds and loads the engine was then run at 3,000 RPM with a load of 500 Watts/0.67 Hp. The spark plug temperature was maintained at about 400 F. Oil level was checked often and the oil was changed after 80 hours. Va.vej were checked often and the oil was changed after 80 hours. Valves were weighed before and after the test to determine the amount of deposits. Using Phillipsi unleaded, untreated fuel, the amount of intake valve deposits was 413 mg.With the treated fuel of Example 1 under the same test conditions, the amount of intake valve deposits was 12 mg.

Example 5 In another test using a 2.3L, 4 cylinder Ford engine and Midcontinent Unleaded base fuel, a test gasoline as in Example 2 was compared to an untreated fuel. Duration of the test was 112 hours. The engine was prepared by cycling at 2,000 RPM with 0-4 BHP for 1 minute then 2,800 RPM at 37 BHP for 3 minutes.

The oil was checked every 8 hours and was changed at 56 hours. At the end of the testing period the intake valves and ports were removed and weighed. With the untreated fuel, the amount of intake valve deposits was 555 mg. Using treated fuel of Example 2, under the same test conditions, the amount of intake valve deposits was 28 mg.

Example 6 In yet another test, a BMW 318 with automatic trans-mission, 1.8L PFI engine was run on untreated and treated fuel using an East Coast regular unleaded gasoline. The engine was run for 10,000 miles. During the testing, the BMW was operated 10% at city speeds in stop and go traffic, 20% at moderate speeds with infrequent stops, and 70% at highway speeds of 65 MPH. To accumulate the required mileage, the BMW was operated for 10 hours a day -- 800 miles per day.

The oil was changed according to the BMW maintenance schedule. The intake valves were removed and weighed after 5,000 and 10,000 miles. Using the untreated fuel, after 5,000 miles, the amount of deposits on the intake valves was 343 mg.

With the treated fuel of Example 3, after 5,000 miles the amount of intake valve deposits was 20 mg, and after 10,000 miles, the amount of intake valve deposits was 24 mg.

Example 7 In another series of :ezts, a Briggs & Stratton engine was used to determine, on a pass or fail basis, which mineral oils would provide a low amount of valve deposits at treat rates of detergent/d ispersant ranging from 30 to 40 (PTB) and mineral oil components ranging from 60 to 10O (PTB).

VISCOSITY VOLATILITY RESULTS MINERAL OIL INDEX (WT.% LOST) (PASS /FAIL) B.P. SEB-78 95 21 Pass Witco 4053-13 44 49 Pass Sun Oil 500-SN li 68 Fail Witco 4058-ML 46 44 Pass Arco 2950 97 > 50 Fail Chevron 500-SN 104 28 Pass Shell HVI-600 91 25 Pass Witco 4053-Heavy 41 30 Pass Texaco ISO-46 101 66 Fail Exxon 325 98 46 Pass Shell HVI-250 90 > 52 Fail Union Oil 450-N 82 42 Fail Exxon 900-SE 74 25 Pass Nlineral Oil Volatility To determine the volatility of the mineral oils suitable for use with this invention, the following procedure is used. Mineral oil (110-135 grams) is placed in a three-neck, 250 mL round-bottomed flask having a threaded port for a thermometer. Such a flask is available from Ace Glass (Catalog No. 6954-72 with 20/40 fittings). Through the center nozzle of the flask is inserted a stirrer rod having a Teflon blade, 19 mm wide x 60 mm long (Ace Glass catalog No. 8085-07). The mineral oil is heated in an oil bath to 300 C for I hour while stirring the oil in the flask at à rate of 150 rpm. During the heating and stirring the free space above the oil in the flask is swept with 7.5 L/hr of inert gas (e.g., nitrogen, argon). The volatility of the oil thus determined is expressed in terms of less than 50%.

Claims (12)

1. A fuel additive concentrate comprising: a) the reaction product of (i) polyamine and (ii) at least one acyclic hydrocarbyl-substituted succinic acylating agent; and b) a mineral oil having a viscosity index of less than about 90 and a volatility of less than 50% as determined by a method described herein.

2. The concentrate of claim 1 further comprising a minor but effective amount of: c) an antioxidant; d) a demulsifier; e) a corrosion inhibitor; f) an aromatic hydrocarbon solvent; or g) any combination of any two or three or all four of components (c), (d), (e) and (f).

3. The concentrate of claim 1 or 2 wherein the weight ratio of (a) to (b) is less than 1:3.

4. The concentrate of claim 1, 2 or 3 wherein the polyamine is triethylene tetramine or a combination of ethylene polyamines which approximate triethylene tetramine.

5. A motor fuel containing a major amount of an unleaded gasoline and a minor amount of the concentrate of any of claims 1 to 4.

6. A motor fuel containing a major amount of unleaded gasoline and a minor amount of a) the reaction product of (i) triethylene tetramine or a combination of ethylene polyamines which approximate triethylene tetramine, and (ii) at least one acyclic hydrocarbyl-substituted succinic acylating agent; b) a mineral oil having a viscosity index of less than about 90 and a volatility of less than 50% as determined by a method described herein; c) an antioxidant; d) a demulsifier; e) a corrosion inhibitor; f) an aromatic hydrocarbon solvent; or g) any combination of any two or three or all four of components (c), (d), (e) and (f) with (a) and (b) wherein the weight ratio of (a) to (b) is in the range of from 1:1.8 to 1:2.2 and wherein the acylating agent contains from 1.12 to 1.25 succinic groups per polyalkylene group.

7. A method for controlling deposits which may develop on internal parts of a gasoline engine comprising providing for use as a fuel composition (I) a major amount of an unleaded gasoline and (II) a minor but effective amount of a deposit control mixture comprising (a) the reaction product of polyamine and at least one acyclic hydrocarbyl substituted succinic acylating agent, and (b) a mineral oil having a viscosity index of less than about 90 and a volatility of less than 50% as determined by a method described herein whereby deposits which may develop on internal parts of a gasoline engine during engine operation are effective controlled.

8. The method of claim 7 wherein the weight ratio of (a) to (b) is in the range of from 1:1.8 to 1:2.2.

9. The method of claim 7 or 8 wherein the polyamine is triethylene tetramine or a combination of ethylene polyamines which approximate triethylene tetramine.

10. The method of claim 7, 8 or 9 wherein the deposit control mixture further comprises c) an antioxidant; d) a demulsifier; e) a corrosion inhibitor; f) an aromatic hydrocarbon solvent; or g) any combination of any two or three or all four of components (c), (d), (e) and (f) wherein the weight ratio of the reaction product of polyamine and at least one acyclic hydrocarbyl substituted succinic acylating agent, to the mineral oil is in the range of from 1:1.8 to 1:2.2 and wherein the molar ratio of acylating agent to polyamine is 1.8:1.

11. A fuel additive concentrate according to claim 1 substantially as described in Example 1.

12. A motor fuel according to claim 5 substantially as described in any one of Examples 1 to 3.