Corrosion inhibitors for fuels and lubricants

A method of inhibiting corrosion in a diesel fuel system, the method comprising:

• passing a diesel fuel through a fuel system, wherein the diesel fuel comprises:
• at least one of an alkali metal, an alkaline earth metal, and zinc in an amount of at least 0.1 ppm by weight;
• a polymer having a statistical average of
• at least 4 acid groups per polymer chain,
• a ratio of carbon atoms per acid group of 7 to 35, and
• an acid number of 80 to 320 mg KOH/g, determined by potentiographic titration with 0.5 molar aqueous hydrochloric acid after heating in 0.5 molar ethanolic potassium hydroxide solution for three hours;
• and
• at least one additive selected from the group consisting of a detergent additive, a carrier oil, a cold flow improver, a lubricity improver, a corrosion inhibitor other than the polymer, a demulsifier, a dehazer, an antifoam, a cetane number improver, a combustion improver, an antioxidant, a stabilizer, an antistat, a metallocene, a metal deactivator, a dye and a solvent.

A method of inhibiting corrosion in a gasoline system, the method comprising:

• passing gasoline through a fuel system, wherein the gasoline comprises:
• at least one of an alkali metal, an alkaline earth metal, and zinc in an amount of at least 0.1 ppm by weight;
• a polymer having a statistical average of
• at least 4 acid groups per polymer chain,
• a ratio of carbon atoms per acid group of 7 to 35, and
• an acid number of 80 to 320 mg KOH/g, determined by potentiographic titration with 0.5 molar aqueous hydrochloric acid after heating in 0.5 molar ethanolic potassium hydroxide solution for three hours;
• and
• at least one additive selected from the group consisting of a lubricity improver, a corrosion inhibitor other than the polymer, a demulsifier, a dehazer, an antifoam, a combustion improver, an antioxidant, a stabilizer, an antistat, a metallocene, a metal deactivator, a dye, and a solvent.