When sourcing an engine oil changer, prioritize the extraction method (manual, pneumatic, or electric). For high-volume workshops, pneumatic (air-powered) models are preferred for speed and efficiency. Ensure the unit has a tank capacity suitable for your needs, typically ranging from 7 to 15 liters for passenger vehicles. Look for high-quality suction probes made of flexible, heat-resistant materials (like reinforced nylon or PTFE) that can withstand oil temperatures up to 60-80°C without collapsing.