If the surface tension of the oil is low, the oil will spread even without help from wind and water currents. Because increased temperatures can reduce a liquid's surface tension, oil is more likely to spread in warmer waters than in very cold waters. Specific gravity is the density of a substance compared to the density of water. Since most oils are lighter than water, they lie flat on top of it. However, the specific gravity of an oil spill can increase if the lighter substances within the oil evaporate.
Viscosity is the measure of a liquid's resistance to flow.
The higher the viscosity of the oil, the greater the tendency for it to stay in one place.