(1) "Carboxylic dispersants" are reaction products of carboxylic acylating agents (acids, anhydrides, esters, etc.) containing at least about 34 and preferably at least about 54 carbon atoms are reacted with nitrogen-containing compounds (such as amines), organic hydroxy compounds (such aliphatic compounds including monohydric and polyhydric alcohols, or aromatic compounds including phenols and naphthols), and/or basic inorganic materials. These reaction products include imide, amide, and ester reaction products of carboxylic acylating agents. Examples of these materials include succinimide dispersants and carboxylic ester dispersants.

The carboxylic acylating agents include alkyl succinic acids and anhydrides wherein the alkyl group is a polybutyl moiety, fatty acids, isoaliphatic acids (e.g. 8-methyl-octadecanoic acid), dimer acids, addition dicarboxylic acids (addition (4+2 and 2+2) products of an unsaturated fatty acid with an unsaturated carboxylic reagent), trimer acids, addition tricarboxylic acids (Empol^® 1040, Hystrene^® 5460 and Unidyme^® 60), and hydrocarbyl substituted carboxylic acylating agents (from olefins and or polyalkenes). In one embodiment, the carboxylic acylating agent is a fatty acid. Fatty acids generally contain from about 8 up to about 30, or from about 12 up to about 24 carbon atoms. Carboxylic acylating agents are taught in U .S. Patent Nos. 2,444,328, 3,219,666 and 4,234,435, the disclosures of which are hereby incorporated by reference.

The amine may be a mono- or polyamine. The monoamines generally have at least one hydrocarbyl group containing 1 to about 24 carbon atoms, with from 1 to about 12 carbon atoms. Examples of monoamines include fatty (C8-30) amines, primary ether amines (SURFAM^® amines), tertiary-aliphatic primary amines ("Primene"), hydroxyamines (primary, secondary or tertiary alkanol amines), ether N-(hydroxyhydrocarbyl)amines, and hydroxyhydrocarbyl amines (Ethomeens" and "Propomeens"). The polyamines include alkoxylated diamines (Ethoduomeens), fatty diamines ("Duomeens"), alkylenepolyamines (ethylenepolyamines), hydroxy-containing polyamines, polyoxyalkylene polyamines (Jeffamines), condensed polyamines (a condensation reaction between at least one hydroxy compound with at least one polyamine reactant containing at least one primary or secondary amino group), and heterocyclic polyamines. Useful amines include those disclosed in U.S. Pat. No. 4,234,435 (Meinhart) and U.S. Pat. No. 5,230,714 (Steckel) which are incorporated herein by reference.

Examples of these "carboxylic dispersants" are described in British Patent 1,306,529 and in many U.S. Patents including the following: 3,219,666, 3,316,177, 3,340,281, 3,351,552, 3,381,022, 3,433,744, 3,444,170, 3,467,668, 3,501,405, 3,542,680, 3,576,743, 3,632,511, 4,234,435, and Re 26,433 which are incorporated herein by reference for disclosure of dispersants.

(2) "Amine dispersants" are reaction products of relatively high molecular weight aliphatic or alicyclic halides and amines, preferably polyalkylene polyamines. Examples thereof are described for Example, in the following U.S. Patents: 3,275,554, 3,438,757, 3,454,555, and 3,565,804 which are incorporated herein by reference for disclosure of dispersants.

(3) "Mannich dispersants" are the reaction products of alkyl phenols in which the alkyl group contains at least about 30 carbon atoms with aldehydes (especially formaldehyde) and amines (especially polyalkylene polyamines). The materials described in the following U.S. Patents are illustrative: 3,036,003, 3,236,770, 3,414,347, 3,448,047, 3,461,172, 3,539,633, 3,586,629, 3,591,598, 3,634,515, 3,725,480, 3,726,882, and 9,980,569 which are incorporated herein by reference for disclosure of dispersants.

(4) Post-treated dispersants are obtained by reacting at carboxylic, amine or Mannich dispersants with reagents such as urea, thiourea, carbon disulfide, aldehydes, ketones, carboxylic acids, hydrocarbon-substituted succinic anhydrides, nitriles, epoxides. boron compounds, phosphorus compounds or the like. Exemplary materials of this kind are described in the following U.S. Patents: 3,200,107, 3,282,955, 3.367,943, 3,513,093, 3,639,242, 3,649,659, 3,442,808, 3,455,832, 3,579,450, 3,600,372, 3,702,757, and 3,708,422 which are incorporated herein by reference for disclosure of dispersants.

(5) Polymeric dispersants are interpolymers of oil-solubilizing monomers such as decyl methacrylate, vinyl decyl ether and high molecular weight olefins with monomers containing polar substituents, e.g. aminoalkyl acrylates or acrylamides and poly-(oxyethylene)-substituted acrylates. Examples of polymer dispersants thereof are disclosed in the following U.S. Patents: 3,329,658, 3,449,250, 3,519,656, 3,666,730, 3,687,849, and 3,702,300 which are incorporated herein by reference for disclosure of dispersants.

The above-noted patents are incorporated by reference herein for their disclosures of ashless dispersants.

Borated dispersants are described in US. patents 3,087,936 and 3,254,025 which are incorporated herein by reference for disclosure of borated dispersants. Also included as possible dispersant additives are those disclosed in U.S. Patents 5, 198,133 and 4,857,214 which are incorporated herein by reference. The dispersants of these patents compare the reaction products of an alkenyl succinimide or succinimide ashless dispersant with a phosphorus ester or with an inorganic phosphorus-containing acid or anhydride and a boron compound.