A settling rate of at least one foulant in oil-based fluids may be determining a settling rate of an oil-based fluid by stirring the fluid during a turbidimetric flocculation titration, which includes solvent dosing and obtaining transmittance measurements of the oil-based fluid. The method may further include stopping the solvent dosing at the onset of flocculation of the foulant(s), stopping the stirring when at least two or more transmittance measurements are substantially similar, and measuring the transmittance of the oil-based fluid to determine a settling rate of the foulant(s). The settling rate may be proportional to an increase in transmittance or decrease in absorbance after the stirring has stopped.