Vegetable oils are an interesting alternative to diesel fuel, as they are a renewable source of energy, have a low sulfur content, are safe to store, do not cause skin ailment. However, using vegetable oils in order to fuel direct injection diesel engines creates problems due to their low heat energy and high viscosity. The purpose of the experiments we made was to determine how the injection equipment behaves when sunflower oils are used and how these oils alter the power indexes of the engine. During the test we used three types of sunflower oil and vegetable oil-diesel oil mixtures; both the injection equipment tests and the engine tests were conducted at 20% load, 40% load and full load. We noticed changes in the injection equipment working parameters (injection pressure, cyclic dose etc.) and in the engine's power indexes (output power and torque, fuel consumption etc.).