Measuring arrangement and method to determine at intervals the usability potential of at least one operational fluid in an engine

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.