91308-P8A-A01 O-Ring (18.3X3.5) - Overview. The 91308-P8A-A01 O-Ring (18.3X3.5) is a crucial sealing component designed for Honda marine engine systems. It supports the oil pump and oil strainer system by providing a reliable seal that prevents fluid leaks, ensuring smooth operation and longevity of the engine. Crafted with exact factory dimensions-18.3 mm inner diameter and 3.5 mm thickness-this genuine Honda O-Ring integrates seamlessly with existing hardware to maintain optimal performance an