To reduce the direct emissions from the building sector caused by the utilization of fossil fuels, electrification of heating has been considered the main strategy for achieving net-zero emissions. Among many heat pump systems, VRF systems have been widely used in commercial buildings. However, VRF systems have a large amount of refrigerant inventory. Therefore, a non-hazardous and low-GWP refrigerant to replace R410A should be dropped in existing R410A-based VRF systems. For the drop-in, compatibility between a new refrigerant and existing oil is the key factor. In this study, R466A was dropped in the R410A compressor test loops to confirm the compatibility. As a result, compressor test loops operated for 500 hours without any problem.