Many scientific studies have demonstrated the harmful effect of chloro-fluoro-carbons (CFC) on the stratospheric ozone layer and their contribution to the green-house effect. Facing this planetary ecological problem, the international community has committed itself to follow the agreement procedures defining the progressive reduction and final withdrawal of CFC production. The chlorine-free substitutes elaborated by chemists, the hydro-fluoro-carbons (HFC), raise difficult problems when applied to the fields of domestic refrigeration and automotive air-conditioning. In these applications, the refrigerants are associated to a lubricant which is necessary for operation of the compressor, Mineral oils which were efficient up to now cannot be used anymore with the new refrigerants TOTAL research teams have been asked to develop a synthetic oil able to solve this new problem. After examining different technics, Neutron Radiography has been considered capable to bring a decisive contribution to this research program. After feasability tests performed in 1989 on a simulation bench at Saclay, dynamic neutron imaging rapidly imposed itself for the observation of polyphasic flows in evaporators under actual operating conditions. Investigation programs scheduled in 1990 and 1991 have permitted to compare the behavior of various oil formulations with HFC. They have led to an industrial product fulfilling all the requested properties