-fractional distillation under reduced pressure could be used to separate the base oils.
-ultracentrifuge might separate oil into layers by mol weight, then you can measure refractive index with interferometer to see if there is a sharp boundary between layers (uniform molecules) or a gradual change
-ultracentrifuge might separate oil into layers by mol weight, then you can measure refractive index with interferometer to see if there is a sharp boundary between layers (uniform molecules) or a gradual change