A recently developed generalized isomorphism approach enables us to account for the critical behavior of thermodynamic and transport properties of fluid mixtures that exhibit continuous crossover from vapor-liquid critical phenomena to liquid-liquid critical phenomena. As an application we show here how the method can be used to predict thermodynamic and transport properties of methane + n-hexane mixtures in the one-phase region near their critical end points based on available liquid-liquid-vapor equilibria data for the mixtures and on the properties of the pure components.