In the paper, a procedure was suggested for making plant oil blends of desirable physico-chemical and performance parameters. There was applied a rule of additivity of parameters of component oils in the blend to get oil products with modified nutritional characteristics. The other objective of the research study was to test the usefulness of the procedure when projecting thermal properties of the blends for deep frying. To make oil blends, plant oils were used that were produced by Oleofarm Ltd. The oil blends were analysed using chromatographic and spectroscopic methods. Their chemical parameters constituted an input dataset to make blends of expected performance properties. It was shown experimentally that it was possible to theoretically project physico-chemical and thermal parameters of the final oil blend. When knowing the chemical parameters of individual blend-forming oils, it is possible to employ them to determine the parameters of the final blend. There were suggested oil compositions for the preparation of advantageous blends to be used for deep frying and salad dressings. Thus there was confirmed the purposefulness of blending the oils in order to make products the  qualities of which could be geared to the specific utility purposes.