The schematic of the electrorheological device is shown in Figure SM1. Figure SM2 displays the viscosity changes during stages S1, S2, and S3 for the three shear rates. Figure SM3 presents the shear stress variation with the shear rate after the application of the electric field, i.e., at the end of stage S3. The methodology used for calculating the crystallized volume fraction of wax and the corresponding values at each measurement temperature are detailed in Section 1. Table SM2 lists the oil viscosity (η_oil) at each measurement temperature with the final viscosity (η_∞) after the application of an electric field.