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Suspensions of fumed silica in polypropylene glycol exhibit shear-thickening under steady shear and “strain-thickening” under oscillatory shear. Strain-thickening refers to a sharp increase in the complex viscosity η* observed at critical combinations of strain-amplitude and frequency. Two regimes of strain-thickening behavior have been found: The first occurs at high critical strains and low frequencies, whereas the second occurs at high critical frequencies and a constant lower strain. Strain-thickening in the first regime can be explicitly correlated with steady shear-thickening, using a modified version of the Cox–Merz rule. Accordingly, strain-thickening data for the complex viscosity η* as a function of the maximum dynamic shear-rate γ₀ω can be superposed against shear-thickening data for the steady viscosity as a function of the steady shear rate. Such a correlation between the two kinds of thickening phenomena …