94109-12000 Drain (12Mm) Washer - Overview. The 94109-12000 Drain (12Mm) Washer is a critical sealing component designed for Honda marine engine systems. Its primary function is to ensure a watertight seal around the 12mm drain plug, preventing oil and fluid leaks that could compromise engine performance and environmental safety. This washer supports the drainage system, maintaining the integrity of oil pan and transmission drain assemblies. Engineered for optimal reliability, it ensures seamles