PURPOSE: To obtain a diesel fuel composition which prevents the deposition of precipitates in diesel engine fuel injectors and thereby cleans the injectors.

CONSTITUTION: A composition is provided comprising a major amount of a diesel fuel oil meeting ASTM Standard Specification D-975 and a minor amount, sufficient to minimize deposit formation on diesel fuel injectors and to maintain design flow rates of the injectors, of a nitrogen-containing dispersant, wherein the number obtained by multiplying the weight-average molecular weight by the present nitrogen of the dispersant ranges from about 45,000 to about 100,000.