Mechanisms by which crude oil components may adsorb on high energy mineral surfaces include polar, acid/base, and ion-binding interactions. Surface precipitation of asphaltic material can further alter surface wetting. Design of controlled experiments to investigate the contributions of different mechanisms is hindered by the lack of simple, well-characterized analogs for crude oils that show even qualitatively similar interfacial properties. As an alternative, we observe the wettability altering tendencies of a variety of crude oils with the aim of relating the fluid/solid interactions to crude oil composition. The mixtures of compounds in crude oils, variability of samples, and changes that can occur during storage, all add to the uncertainties of mechanistic studies with crude oils. Nevertheless, consistent trends can be identified.