At least one embodiment of the inventive technology may involve the intentional changing of the stability of an emulsion from a first stability to a more desired, second stability upon the addition of a more aromatic asphaltene subfraction (perhaps even a most aromatic asphaltene subfraction), or a less aromatic asphaltene subfraction (perhaps even a least aromatic asphaltene subfraction) to a emulsion hydrocarbon of an oil emulsion, thereby increasing emulsion stability or decreasing emulsion stability, respectively. Precipitation and redissolution or sorbent-based techniques may be used to isolate a selected asphaltene subfraction before its addition to an emulsion hydrocarbon when that hydrocarbon is part of an emulsion or an ingredient of a yet-to-be-formed emulsion.