A method and a device for determination of the stability or storability of oil, wherein the stability of oil is determined by measuring the intensity of light scattering from the oil surface, when an asphalteneflocculating liquid is added to the oil sample for determining the stability of the oil. In an advantageous embodiment of the method the intensity of scattered light is directed onto the surface of the oil sample by using a suitable prism. The invention allows implementation of a fully automatically operating analyzer for determining the stability of oil. A closed measuring system is brought about that solves the explosion protection problem which is important in oil refining.