Lubricating oil compositions comprising a biodiesel fuel and a dispersant

A method of lubricating a diesel engine fueled at least in part with a biodiesel fuel which comprises operating the engine with a lubricating oil composition contaminated with at least about 0.3 wt % of a biodiesel fuel or a decomposition product thereof, based on the total weight of the lubricating oil composition, wherein the lubricating oil composition comprises:

• comprising a major amount of base oil of lubricating viscosity;
• and a polysuccinimide dispersant, said dispersant prepared by the process which comprises reacting
• (A) at least one of the following copolymers:
• (i) a copolymer obtained by free radical copolymerization of components comprising:
• (a) at least one monoethylenically unsaturated C3-C28 monocarboxylic acid or ester thereof, or C4-C28 dicarboxylic acid, anhydride or ester thereof;
• (b) at least one 1-olefin comprising about 2 to 40 carbon atoms or at least one polyolefin comprising about 4 to 360 carbon atoms and having a terminal copolymerizable group in the form of a vinyl, vinylidene or alkyl vinylidene group or mixtures thereof;
• and
• (c) at least one monoolefin compound which is copolymerizable with the monomers of (a) and (b) and is selected from the group consisting of:
• (1) an alkyl vinyl ether and an allyl alkyl ether where the alkyl group is hydroxyl, amino, dialkylamino or alkoxy substituted or is unsubstituted, and containing 1 to 40 carbon atoms;
• (2) an alkyl amine and an N-alkylamide of a monoethylenically unsaturated mono- or dicarboxylic acid of 3 to 10 carbon atoms wherein the alkyl substituent contains 1 to 40 carbon atoms;
• (3) a N-vinylcarboxamide of carboxylic acids of 1 to 8 carbon atoms;
• (4) a N-vinyl substituted nitrogen-containing heterocyclic compound;
• and
• (5) at least one 1-olefin comprising about 2 to 40 carbon atoms or at least one polyolefin comprising about 4 to about 360 carbon atoms and having a terminal copolymerizable group in the form of a vinyl, vinylidene or alkyl vinylidene group or mixtures thereof, provided that the olefin employed is not the same as the olefin employed in (i)(b);
• (ii) a copolymer obtained by reacting compound (i)(a) and compound (i)(b) in the presence of a free radical initiator;
• (iii) a copolymer obtained by (a) reacting compound (i)(a) with compound (i)(b) or (i)(c) in a non-free radical catalyzed reaction in the presence of copolymer (i) or copolymer (ii) or both;
• or by (b) contacting copolymer (i) or copolymer (ii) or both with the non-free radical catalyzed reaction product of compound (i)(a) and compound (i)(b) or (i)(c);
• with
• (B) at least one ether compound selected from the group consisting of an ether polyamine, a polyether polyamine, a polyether amino alcohol, a polyether amino thiol, and a polyether polyol;
• and
• (C) at least one aromatic amine;
• and
• wherein the amount of said dispersant present in the lubricating oil composition is at least about 2 wt. % actives, based on the total weight of the lubricating oil composition.

A method for inhibiting viscosity increase in a diesel engine fueled at least in part with a biodiesel fuel which comprises operating the engine with a lubricating oil composition contaminated with at least about 0.3 wt % of a biodiesel fuel or a decomposition product thereof, based on the total weight of the lubricating oil composition, wherein the lubricating oil composition comprises:

• comprising a major amount of base oil of lubricating viscosity;
• and a polysuccinimide dispersant, said dispersant prepared by the process which comprises reacting
• (A) at least one of the following copolymers:
• (i) a copolymer obtained by free radical copolymerization of components comprising:
• (a) at least one monoethylenically unsaturated C3-C28 monocarboxylic acid or ester thereof, or C4-C28 dicarboxylic acid, anhydride or ester thereof;
• (b) at least one 1-olefin comprising about 2 to 40 carbon atoms or at least one polyolefin comprising about 4 to 360 carbon atoms and having a terminal copolymerizable group in the form of a vinyl, vinylidene or alkyl vinylidene group or mixtures thereof;
• and
• (c) at least one monoolefin compound which is copolymerizable with the monomers of (a) and (b) and is selected from the group consisting of:
• (1) an alkyl vinyl ether and an allyl alkyl ether where the alkyl group is hydroxyl, amino, dialkylamino or alkoxy substituted or is unsubstituted, and containing 1 to 40 carbon atoms;
• (2) an alkyl amine and an N-alkylamide of a monoethylenically unsaturated mono- or dicarboxylic acid of 3 to 10 carbon atoms wherein the alkyl substituent contains 1 to 40 carbon atoms;
• (3) a N-vinylcarboxamide of carboxylic acids of 1 to 8 carbon atoms;
• (4) a N-vinyl substituted nitrogen-containing heterocyclic compound;
• and
• (5) at least one 1-olefin comprising about 2 to 40 carbon atoms or at least one polyolefin comprising about 4 to about 360 carbon atoms and having a terminal copolymerizable group in the form of a vinyl, vinylidene or alkyl vinylidene group or mixtures thereof, provided that the olefin employed is not the same as the olefin employed in (i)(b);
• (ii) a copolymer obtained by reacting compound (i)(a) and compound (i)(b) in the presence of a free radical initiator;
• (iii) a copolymer obtained by (a) reacting compound (i)(a) with compound (i)(b) or (i)(c) in a non-free radical catalyzed reaction in the presence of copolymer (i) or copolymer (ii) or both;
• or by (b) contacting copolymer (i) or copolymer (ii) or both with the non-free radical catalyzed reaction product of compound (i)(a) and compound (i)(b) or (i)(c);
• with
• (B) at least one ether compound selected from the group consisting of an ether polyamine, a polyether polyamine, a polyether amino alcohol, a polyether amino thiol, and a polyether polyol;
• and
• (C) at least one aromatic amine;
• and
• wherein the amount of said dispersant present in the lubricating oil composition is at least about 2 wt. % actives, based on the total weight of the lubricating oil composition.