When evaluating oil radiator heaters, prioritize heating power (typically 1500W to 2500W) and the number of fins (7, 9, 11, or 13), as these directly impact heat distribution efficiency. Ensure the unit features high-quality diathermic oil that never needs refilling and is sealed in heavy-gauge steel fins to prevent leakage. For the control system, look for adjustable thermostats and multiple heat settings (Low, Medium, High) to optimize energy consumption. Additionally, verify the gauge of the power cord and the quality of the castor wheels for durability and mobility.