08739-M0500 Oil (5gal) (5gal) - Overview. The 08739-M0500 Oil (5gal) (5gal) is a 5-gallon container of specialized gear case oil designed for Honda marine engine lubrication systems. This genuine Honda OEM product plays a critical role in maintaining the optimal operation and durability of outboard motor lower units by providing superior lubrication and protection against wear and corrosion. Engineered to meet factory specifications, this oil ensures seamless integration with existing parts, mai