【Replace OE Number】F81Z8A080AA, F81Z8A080-AA, F81A-8A080-AD. Prevents Coolant Spillage and Waste. Improves Heat Dissipation Efficiency of the Cooling System. The reservoir separates vapor and air from the coolant, by doing so, the reservoir ensures that coolant circulates fully between the engine and the radiator, maximizing heat transfer and helping to prevent engine overheating—especially during high-load conditions.