40106-ZW9-730 Oil Case Grommet B - Overview. The 40106-ZW9-730 Oil Case Grommet B is a vital component in Honda marine engine systems. It serves as a durable rubber seal designed to prevent oil leaks in the oil case area, helping maintain reliable engine operation. By effectively sealing critical points, it ensures seamless integration with existing parts, maintaining optimal performance and durability.. Key Features. Precisely molded rubber grommet functioning as a seal in the oil case system..