An experimental investigation of ε' and tanδ for oils of a number of deposits in Russia was performed. The relative permittivity and the tangent of dielectric loss angle of oils were measured by an E4-11 Q-meter. The voltage of given frequency from the Q meter was applied to measuring capacitor plates. The preassigned temperature was provide by the circulation of thermostatic liquid in the thermostat-jacket system of the measuring capacitor. Investigations revealed that the values of ε' hardly vary in the process of degassing. The most significant changes are observed in the case of tanδ. The curves indicate that tanδ of degassed oil is higher than that of non-degassed oil. The possibility of orientation for polar molecules is maximal. It is also observed that the amount of released gas might be determined without analyzing the liquid for gas content, by measuring the dielectric characteristics of oil before and after the field impact.