A corrosion inhibitor formulation comprising: a) at least one quaternary ammonium salt; b) at least one fatty acid methyl ester; c) at least one viscosity reducing agent selected from the group consisting of isopropanol, propanol, ethanol, toluene, benzene, hexane, kerosene, diesel, propargyl alcohol, and combinations thereof; and d) at least one solubilizing agent selected from the group consisting of acetic acid, hydroxyacetic acid, tannic acid, 2,6-pyridine dicarboxylic acid, lactic acid, glucono 6-lactone (gluconic acid), 2-puroic acid, thiophene-2-carboxylic acid, 2,3-pyridine dicarboxylic acid, phosphonoacetic acid, thiophene-2-acetic acid, mercaptoacetic acid, propionic acid, butanoic acid, pentanoic acid, benzoic acid, and combinations thereof, wherein the at least one quaternary ammonium salt to the at least one fatty acid methyl ester weight ratio is in the range of 1:0.2 - 1:5.0, wherein the at least one quaternary ammonium salt is a combination of alkyldimethylbenzylammonium chloride and a compound selected from the group consisting of Formula I, and Formula II, wherein, Y is selected from O, -NH, or -NR 3 ; X is selected from O or S; A is selected from fluoro, chloro, bromo, iodo, hexafluorophosphate, OH - , HCO 3- , CO 3 2- , R 4 COO - , R 4 SO 4 - , or R 4 SO 3 - , wherein R 4 is selected from the group consisting of hydrogen, C 1-6 alkyl, and C 5-10 aryl, wherein C 1-6 alkyl, and C 5-10 aryl are optionally substituted with hydroxyl, nitro, halogen, alkyl, aryl, or -COOR 4 ; R 1 is C 1-20 alkyl, C 2-20 alkenyl, C 2-20 alkynyl, and C 5-6 aryl, wherein, C 1-20 alkyl, C 2-20 alkenyl, C 2-20 alkynyl, and C 5-6 aryl are optionally substituted with C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, and C 5-6 aryl; and n and m are independently 5 to 10; and R 2 and R 3 are independently C 1-6 alkyl. a) at least one quaternary ammonium salt; b) at least one fatty acid methyl ester; c) at least one viscosity reducing agent selected from the group consisting of isopropanol, propanol, ethanol, toluene, benzene, hexane, kerosene, diesel, propargyl alcohol, and combinations thereof; and d) at least one solubilizing agent selected from the group consisting of acetic acid, hydroxyacetic acid, tannic acid, 2,6-pyridine dicarboxylic acid, lactic acid, glucono 6-lactone (gluconic acid), 2-puroic acid, thiophene-2-carboxylic acid, 2,3-pyridine dicarboxylic acid, phosphonoacetic acid, thiophene-2-acetic acid, mercaptoacetic acid, propionic acid, butanoic acid, pentanoic acid, benzoic acid, and combinations thereof, wherein the at least one quaternary ammonium salt to the at least one fatty acid methyl ester weight ratio is in the range of 1:0.2 - 1:5.0, wherein the at least one quaternary ammonium salt is a combination of alkyldimethylbenzylammonium chloride and a compound selected from the group consisting of Formula I, and Formula II, wherein, Y is selected from O, -NH, or -NR 3 ; X is selected from O or S; A is selected from fluoro, chloro, bromo, iodo, hexafluorophosphate, OH - , HCO 3- , CO 3 2- , R 4 COO - , R 4 SO 4 - , or R 4 SO 3 - , wherein R 4 is selected from the group consisting of hydrogen, C 1-6 alkyl, and C 5-10 aryl, wherein C 1-6 alkyl, and C 5-10 aryl are optionally substituted with hydroxyl, nitro, halogen, alkyl, aryl, or -COOR 4 ; R 1 is C 1-20 alkyl, C 2-20 alkenyl, C 2-20 alkynyl, and C 5-6 aryl, wherein, C 1-20 alkyl, C 2-20 alkenyl, C 2-20 alkynyl, and C 5-6 aryl are optionally substituted with C 1-6 alkyl, C 2-6 alkenyl, C 2-6 alkynyl, and C 5-6 aryl; and n and m are independently 5 to 10; and R 2 and R 3 are independently C 1-6 alkyl. <EOS>