A measuring and testing system for a test piece (1) with at least one operational fluid, particularly to test an internal combustion engine, is provided with at least one measuring arrangement connected to a space (2) of the test piece (1) containing operational fluid, and comprising a partial measuring arrangement (4, 5, 6) for the quantity parameter of the operational fluid and at least one additional partial measuring arrangement (6, 7) for at least one quality parameter for the characterization of the physical and/or chemical condition of the operational fluid, as well as a control and evaluation unit (6) connected to the measuring arrangement. An evaluation logic is implemented in the evaluation unit (6) whereby said evaluation logic links the quantity parameters with at least one condition parameter according to a predefinable relationship and determines the usability potential of the operational fluid to be able to give in a systematic and simple manner also information about the admissibility and possible validity of the parameters of the operational fluids and possibly about other measuring and testing results.