Double layer Expansion (DLE) is proposed as one of the mechanisms responsible for Improved Oil Recovery (IOR) during Low Salinity Water Flooding (LSWF). This expansion is triggered by the overlap between the diffuse double layers. We performed molecular simulation to study this phenomenon where both kaolinite and montmorillonite are used as substrates contacting water with varying concentration of monovalent and divalent ions. Our results, and several molecular simulations, have confirmed that the location of the adsorption planes is independent of the ionic strength. However, the potential developed on these surfaces and how it decays depends on both the ionic strength and ion nature. A shrinkage is observed in the double layer for the case of low salinity, supported by both film thickness estimations and interaction energy analysis. This shrinkage, which contradicts the prevailing assumption, is consistent with molecular simulation studies, and casts some doubts on the efficiency of DLE as a mechanism for explaining IOR observed during LSWF. This brings into question the role of double layer expansion in enhancing oil recovery, and raises the need to investigate other mechanisms that could be responsible for the experimental and field observations made in this area.