A destabilization study of water-in-crude oil emulsions based on crude oils from the Norwegian Continental Shelf is reported. It is found that medium-chain alcohols (1-butanol and benzyl alcohol) and amines are speeding up the separation of water. The destabilization mechanisms in these two cases seem to be fundamentally different. The alcohols seem to modify the rigidity of the interfacial film by a diffusion/partitioning process while the amines show a strong and specific interaction with interfacial groups, hence hydrophilizing the whole film. Observed trends in the time-dependence of the interfacial tension upon addition of alcohols and amines support these suggestions to destabilization mechanisms. Data for a commercial demulsifier Dissolvan 4455 are also given.