When a dispersant is applied to an oil slick, its effectiveness in dispersing the spilled oil depends on various factors such as oil properties, wave mixing energy, temperature of both oil and water, and salinity of the water. Estuaries represent water with varying salinities. In this study, three salinity values in the range of 10-34 ppt were investigated, representing potential salinity concentrations found in typical estuaries. Three oils were chosen to represent light refined oil, light crude oil and medium crude oil. Each of the oils was tested at three weathering levels to represent maximum, medium and zero weathering. Two dispersants were chosen for evaluation. A modified trypsinizing flask termed the Baffled Flask was used for conducting the experimental runs. A full factorial experiment was conducted for each oil to investigate the effect of salinity on three environmental factors: temperature (2 levels), oil weathering (3 levels) and mixing energy (150,200 and 250 rpm). Each experiment was replicated four times in order to evaluate the accuracy of the test. Evaluations were conducted to study the effect of different variables like salinity, weathering, mixing speed and temperature on dispersant effectiveness. Statistical analysis of the data was performed separately on each of the nine oil-dispersant combinations, which revealed the significant factors for each of the combinations. A linear regression model was fit to the experimental data collected.