I dont know the answer to this because i cant find it on the net or textbook, i need to know a type of fluid that is one where density varies throughout the fluid system? (Eg, a fluid system of oil and water among others)
Most liquids are relatively incompressible, meaning that density doesn't change much under pressure. If you need an example of one fluid at multiple densities, look at what happens to air at high altitudes.
The density of the atmosphere (or other fluid columns) increases with depth.Density variations occur in fluids due to convection currents.You have already mentioned oil and water and you could extend this to any system of immiscible fluids.