Since the Exxon Valdez accident in 1987, there has been renewed interest in better understanding and predicting the fate and transport of crude oil in coastal environments. In South Florida, the interest has increased because of regulatory actions that, among other issues, address oil and fuel releases in water bodies. In this study, experimental design and results are described on the effect of weathering of an Arabian crude oil on its simulated dispersion in a saline water. Time-dependent changes of rheological and chemical properties of this oil are reported under controlled weathering conditions. Selected organic compounds are used to measure oil dispersion in simulated ocean turbulence conditions. Results show an increase in viscosity and density and a decrease in interfacial surface tension between oil and water, probably as a result of evaporation of lower molecular weight hydrocarbons. Total and aromatic hydrocarbon concentrations under mixing conditions are a function of weathering time, depth from the water surface, and duration of mixing. These results have provided fundamental information to enhance future experimental efforts and to assist in the conceptual development of ecotoxicological assessments of oil spills.