The mechanism of action of additives for diesel fuel is studied in terms of molecular interactions. Using UV spectrophotometry, electron microscopy, conductivity, and other methods, we give experimental evidence of these interactions in diesel, including in the presence of additives. It is shown for the first time that the efficiency of diesel additives depends on the formation of new structures, such as charge-transfer complexes. Based on the analysis of the chemical structure of various additives, we make a conclusion that they all are classified as surfactants. It is known that diesel fuels are disperse fuel systems. Therefore, the experimental data on decreasing surface tension at the interface of a disperse fuel system in the presence of additives indicate that the additives are fuel stabilizers. A conclusion is drawn that additives that differ in chemical structure and have different functional purposes, including multifunctional additives, operate in a fuel disperse system by a common mechanism that is similar to the action of surfactants in classical disperse systems. This mechanism is associated with an increase in the stability of a disperse fuel system in the presence of additives and, as a consequence, with an improvement in its quality.