In this paper, the F-SAC model was extended and modified in order to better represent the very low mutual solubility of hydrocarbons (alkanes, cycloalkanes, alkenes, cycloalkenes and aromatics) and water. Infinite dilution activity coefficient and liquid-liquid equilibrium data were considered. A new parameter for the computation of the water self-association energy was proposed, enabling a better agreement with temperature dependent experimental data. The results were compared with some UNIFAC variants, found in the literature. For the systems studied, the proposed method performed better, including the quantitative representation of the experimentally observed minimum solubility point. None of UNIFAC models tested was capable of predicting such behavior. Finally, the model was used to predict the water solubility in petroleum fractions by using a pseudo-components approach. With this approach, the F-SAC model was capable of satisfactory represent the experimental data.