This dataset contains the raw experimental data obtained from the oil flow variation tests in high-temperature heat pump mode conducted in a reversible Organic Rankine Cycle system. The measurements were performed at the Chair of Energy Systems, Technical University of Munich. The analyzed results were presented at the 8th International Seminar on ORC Power Systems (2025) and the corresponding publication ("Working fluid/oil separation in a reversible ORC test rig with a twin-screw machine - Lessons learned and remaining challenges") is available in the conference proceedings.