Methods to reduce frequency of diesel particulate filter regeneration

A method of reducing measured regeneration frequency of a diesel particulate filter in a vehicle combusting diesel fuel, the method comprising:

• (a) combusting a diesel fuel in a vehicle engine, wherein the vehicle includes a diesel particulate filter associated with the engine and wherein the diesel particulate filter requires regeneration thereof, the diesel fuel having less than about 50 ppm of sulfur and one or more additives selected from
• a quaternary ammonium cationic salt obtained from amines or polyamines and dialkyl oxalate, alkyl salicylate, or a combination thereof;
• having the structure of Formula VII:
• [(R18)(R19)N—(CH2)n—Xm—(CH2)n—Xm—(CH2)n—N⊕(R15)(R16)(R17)]M⊖ (Formula VII)
• wherein each X is a bivalent moiety selected from the group consisting of —O—, —N(R20)—, —C(O)—, —C(O)O—, or —C(O)NR20;
• each R15, R16, and R17 are independently alkyl groups containing 1 to 8 carbon atoms;
• R18 and R19 are independently selected from an alkyl group, acyl group, or a hydrocarbyl substituted acyl group, the hydrocarbyl substituent of one or both of R18 and R19 having a number average molecular weight of about 700 or greater;
• R20 is independently a hydrogen or a group selected from C1-6 aliphatic, phenyl, or alkylphenyl;
• each m is independently an integer of 0 or 1 with at least one m being 1;
• each n is independently an integer of 1 to 10;
• and M⊖ is a carboxylate;
• (b) regenerating the diesel particulate filter while combusting the diesel fuel;
• and
• (c) comparing the frequency of regeneration of the diesel particulate filter when combusting the diesel fuel comprising the one or more additives with the frequency of regeneration of the diesel particulate filter when combusting a diesel fuel which is devoid of the one or more additives;
• wherein the frequency of regenerations per 1000 miles of the diesel particulate filter when combusting the diesel fuel comprising the one or more additives is lower than a frequency of regenerations per 1000 miles of the diesel particulate filter when combusting a diesel fuel in the engine devoid of the one or more additives.