Among many technical improvements done over past decades, passing from a «standard oil» to an enhanced lubricant that reduces the mechanical losses in vehicles powertrains has shown significant fuel savings in the automotive industry, typically in a magnitude of 2 to 5%. Considering those encouraging results, oil manufacturers are spurred to extend their range of fuel saving lubricants to agricultural equipments. Optimizing a lubricant to the agricultural framework requires to understand the working conditions and vehicle running points. As a purpose of better describing the working dynamics, an experimental tractor has been specifically equipped to monitor the power distribution along a whole year, covering all the related field operations. The data acquisition campaign is based on both analog and digital signals recordings, combining the information available on-board and the one from external additional measuring devices. Statistical data analysis enables later to discriminate the applications and identify the specific running points according to the different working phases along the field, basically comprising crop line and maneuvers. Characterizing this dually working profile is used to propose operational efficiency indicators. A parametric model is defined according those alternating phases. Its computation requires to set the transmission efficiency as an input parameter. Its sensibility regarding the employed lubricant is therefore measured over benchtests by simulating effective running conditions. For validation purposes, the model is applied to a plowing operation. The robustness of the proposed method is discussed by a sensibility analysis of the indicators to the chosen test parameters. We investigate the lubricant effect on the transmission efficiency, and finally relate it to an operational efficiency, expressed in field efficiency [ha/h] and area related consumption [l/ha].