Results of investigation the impact of an admixture of the Jet A‑1 aviation turbine fuel on the density, kinematic viscosity, acid number, and oxidation stability of rapeseed methyl esters (RME) have been presented. A growth in the Jet A‑1 content of the biodiesel blend has been found to cause a reduction in the density, acid number, and kinematic viscosity of the blend and to raise its oxidation stability. These relations have been presented in the form of regression equations as functions of the Jet A‑1 content in the blend, for this content varying from 0 % to 50 % by volume. Moreover, the impact of the access of air, sunlight, heat, and water on the characteristics of pure fuels and their blends was examined and the test results have been shown. It has been found that the adding of an admixture of the Jet A‑1 aviation fuel reduces the intensity of RME ageing and that it may be one of the methods to improve the functional RME characteristics, including the oxidation stability of this fuel.