We have recently introduced several important improvements in the measurement of distillation Curves of complex fluids, The modifications to the classical measurement provide for (1) a composition-explicit data channel for each distillate fraction (for qualitative, quantitative, and trace analysis): (2) temperature measurements that are true thermodynamic state points that can be modeled with an equation of state; (3) temperature, volume, and pressure measurements Of low uncertainty Suitable for equation of state development (4) consistency with a century of historical data; (5) an assessment of the energy content of each distillate fraction and (6) a corrosivity assessment of each distillate fraction. We hive applied the new method to the measurement of rocket propellant, gasolines, jet fuels, and hydrocarbon crude oils. In this paper. we present the application of the technique to representative batches of ultra low sulfur diesel fuel (ULSD) and mixtures of this diesel fuel with two of the more promising oxygenating agents; namely, dimethyl carbonate and diethyl carbonate. The addition of oxygenates, although more familiar in gasoline fuel systems, is also of great interest in the diesel fuel community, since it provides an opportunity to decrease particulate emissions. The potential of designing new fuel mixtures critically depends oil knowledge of the thermophysical properties of the fluids. The volatility, its provided by the distillation curve method we apply, is part of that knowledge base. We present herein the distillation curves its a function of additive starting concentration and the concurrent analytical information. We noted that even after the oxygenates have distilled out of the mixtures. there is a persistent depression in the temperature. Ail explanation in terms of the Helmholtz free energy equation of state model is advanced.