40105-ZW9-831 Oil Case Grommet A - Overview. The 40105-ZW9-831 Oil Case Grommet A is an essential sealing component designed specifically for Honda marine engine systems. It functions within the oil case system to provide a reliable, leak-proof connection that preserves engine lubrication integrity and supports smooth engine operation. Manufactured to exact Honda factory specifications, this grommet ensures seamless integration with existing parts, maintaining optimal performance and durability.