Yamalube GL5 SAE 90 – High-Performance Gear Oil for High-Power Outboards

Yamalube GL5 SAE90 gear oil is the highest-performing transmission lubricant in Yamaha’s lineup, formulated to meet the demands of today’s powerful engines. Initially developed for the Yamaha V8 F350 outboard (350 HP) – one of the most powerful outboards on the market – this oil is the natural choice for all Yamaha sterndrive systems as well as any other brand that requires a GL-5 grade oil. The formula provides an exceptionally durable oil film capable of maintaining its integrity under heavy pressure and sudden shock loads that occur during high-speed operation and intense use (such as rapid acceleration or running in rough seas).

Beyond outstanding mechanical protection, Yamalube GL5 also cares for the chemical well-being of your gearbox. It contains advanced anti-rust inhibitors to counteract the effects of saltwater exposure, and anti-oxidant additives to prevent thickening and the formation of varnish deposits on gears and seals. This ensures seals remain clean and pliable, minimizing the risk of leaks and failures. The oil’s low friction characteristics also contribute to smoother gear shifts across the full temperature spectrum – from cold startups to extended wide-open-throttle runs.

Applications & Recommendations:

• High-horsepower outboards: Recommended for Yamaha V6 and V8 models (e.g. F225, F250, F300, F350) and equivalent engines from other manufacturers that call for GL-5 oil. Also suitable for racing and commercial boats, where engines operate under extreme load and standard oils won’t hold up.
• Sterndrives and inboard gearcases: Ideal for all Yamaha sterndrive systems (and other brands’ sterndrives) where high power and torque demand the toughest lubrication. It helps maintain smooth gear operation and protects bevel gear sets from slipping and wear.
• 1 L bottle – handy container for individual oil changes on a single engine. One 1L bottle typically covers all or most of the gearcase capacity of a large outboard. Use this size for periodic changes or for topping off as needed.
• 20 L drum – economical bulk option for professional users, marine workshops, or owners of multiple vessels. This large container provides enough oil for multiple changes, reducing the cost per liter and ensuring you always have the proper oil on hand for your fleet. It comes with a spout or can be fitted with a pump for easy dispensing.
• Maintenance tip: Due to the specialized additives aimed at maximum protection, Yamalube GL5 SAE90 may appear slightly darker or have a stronger odor than standard oils – this is normal for GL-5 class lubricants. For high-power engines, it’s advisable to change the gear oil every 50-100 hours or at the start of each season (whichever comes first). Always inspect the old oil for water intrusion (a milky appearance), which could indicate a seal issue. Regular changes with genuine oil will keep your drivetrain in top condition.
• Compatibility: Can be used in all marine gearcases requiring SAE 90 API GL-5 oil. If your engine’s lower unit has bronze/copper components, check the manufacturer’s guidelines – older equipment with such parts may recommend GL-4 instead (see Yamalube GL4 SAE90). For all other applications, the GL5 formula provides the highest level of protection available.