The effects of SO42- and Mg2+ on the adsorption/displacement of stearic acid (SA), N,N-dimethyldodecylamine (NN-DMDA) and asphaltene, as oil soluble additives, onto or from calcite, quartz, and clay minerals are addressed in this paper. Thermal gravimetric analysis, isothermal watervapor adsorption, and contact angle methods are used to determine the extent of surface modification and evaluate the hydrophilicity/hydrophobicity of the modified powders and minerals, respectively. The experimental results of the modified mineral surfaces are analyzed using a suggested wettability index based on water, vapor adsorption isotherm and contact angle. It is interesting to observe that SO42- and Mg2+ ions enhance hydrophilicity characteristic of the modified calcite surface while SO42- ions have insignificant effect on adsorption of the tested polar components on the silicate minerals. Mg2+ ions enhance the hydrophilicity of quartz and kaolinite surfaces modified by N,N-dimethyldodecylamine. On the other hand Mg2+ ions increase the hydrophobicity of silicate minerals when asphaltene is the surface modifying component. This maybe cue to bridging of the hydrated Mg2+ ions with asphaltene. The suggested bridging mechanism is also consistent in the case of alteration of calcite surface with asphaltene, however to lesser extent due to the more affinity toward calcite surfaces.