The oil-filling stage in electric oil heater production is a critical operation impacting product safety, thermal performance, and long-term reliability. Thermal oil acts as both a heat transfer medium and an electrical insulator. Deviations in oil quality or filling conditions may cause latent defects appearing only during operation. Contamination, especially moisture ingress, reduces dielectric strength and accelerates oil degradation. Air entrapment during filling can cause uneven temperature distribution, localized overheating, and premature heating element failure. Variability from manual or poorly controlled filling increases the risk of underfilling or overfilling, affecting compliance with technical standards. This paper examines the main technical issues in oil filling, including risks, process control challenges, and safety concerns. From an IT perspective, the process demands precise measurement, system reliability, and integration of control software, sensors, and data acquisition platforms. Software misconfiguration, communication errors, or inadequate validation may lead to incorrect filling parameters and delayed fault detection. The paper outlines key functional and user-interface requirements for IT systems supporting and stabilizing the oil-filling process.