A fuel additive for fuel formulations comprising calcium sulfonates in an amount effective to limit or eliminate valve seat recession in engines utilizing such fuel formulations. The fuel additive may also include a detergent, particularly in an amount to enhance the VSR limiting effect of the calcium sulfonates. Also included are fuel formulations containing calcium sulfonates in a concentration effective to limit vale seat recession in engines utilizing the fuel formulations. Methods for treating VSR in piston engines are also provided.

A fuel additive composition, including: (a) one or more copolymer(s) including: at least one unit of the following formula (I), where u=0 or 1, E=—O— or —N(Z)—, or —O—CO—, or —CO—O— or —NH—CO— or —CO—NH—, where Z represents H or a C1-C6 alkyl group, G represents a group selected between a C1-C34 alkyl group, aromatic ring, aralkyl including at least one aromatic ring and at least one C1-C34 alkyl group, and at least one unit of the following formula (II), where R1″ is selected between a hydrogen atom and a methyl group, Q is selected between an oxygen atom and a group —NR′—, where R′ is selected between a hydrogen atom and C1-C12 hydrocarbon chains, R includes a C1-C34 hydrocarbon chain substituted with at least one quaternary ammonium, (b) one or more amines substituted with a polyalkenyl group, and (c) at least one carrier oil.

A fuel additive composition includes: (a) one or more copolymers including:

at least one unit of formula (I) below:

##STR00001##

with u=0 or 1, E=—O— or —N(Z)—, or —O—CO—, or —CO—O— or —NH—CO— or —CO—NH—, with Z representing H or a C.sub.1-C.sub.6 alkyl group, G represents a group chosen from a C.sub.1-C.sub.34 alkyl, an aromatic nucleus, an aralkyl including at least one aromatic nucleus and at least one C.sub.1-C.sub.34 alkyl group, and —at least one unit of formula (II) below:

##STR00002##

in which R.sub.1″ is chosen from a hydrogen atom and a methyl group, Q is chosen from an oxygen atom and a group —NR′— with R′ being chosen from a hydrogen atom and C.sub.1 to C.sub.12 hydrocarbon-based chains, R comprises a C.sub.1 to C.sub.34 hydrocarbon-based chain substituted with at least one quaternary ammonium group.

A fuel additive composition, including: (a) one or more copolymer(s) including: at least one unit of the following formula (I), where u=0 or 1, E=-O or N(Z), or OCO, or COO or NHCO or CONH, where Z represents H or a C1-C6 alkyl group, G represents a group selected between a C1-C34 alkyl group, aromatic ring, aralkyl including at least one aromatic ring and at least one C1-C34 alkyl group, and at least one unit of the following formula (II), where R1 is selected between a hydrogen atom and a methyl group, Q is selected between an oxygen atom and a group NR, where R is selected between a hydrogen atom and C1-C12 hydrocarbon chains, R includes a C1-C34 hydrocarbon chain substituted with at least one quaternary ammonium, (b) one or more amines substituted with a polyalkenyl group, and (c) at least one carrier oil.

A composition of additives for fuel including: one or more copolymer(s) including:at least one unit of the following formula (I): wherein R1 is selected from hydrogen and methyl group, R2 is selected from C1 to C34 hydrocarbon-based chains, an aromatic ring, an aralkyl containing at least one aromatic ring and at least one C1-C34 alkyl group, andat least one unit of following formula (II): wherein R1 is selected from hydrogen and methyl group, Z is selected from the oxygen atom and NR group with R being selected from a hydrogen atom and C1 to C12 hydrocarbon-based chains, G includes a C1 to C34 hydrocarbon-based chain substituted with at least one quaternary ammonium group and optionally one or more hydroxyl groups, group G also possibly containing one or more nitrogen and/or oxygen atoms and/or carbonyl groups 25 at least one compound selected from succinimides substituted with a hydrocarbon-based chain.

A fuel additive for fuel formulations comprising calcium sulfonates in an amount effective to limit or eliminate valve seat recession in engines utilizing such fuel formulations. The fuel additive may also include a detergent, particularly in an amount to enhance the VSR limiting effect of the calcium sulfonates. Also included are fuel formulations containing calcium sulfonates in a concentration effective to limit vale seat recession in engines utilizing the fuel formulations. Methods for treating VSR in piston engines are also provided.