YAMAHA Marine Lower Unit Gearcase Lube - 1 Gallon SAE 90 (80W-90) GL-4, Corrosion-Resistant

Yamalube Marine Lower Unit Gearcase Lube is a heavy-duty SAE 90 (80W-90) gear oil formulated to protect outboard lower units up to 250 HP from wear, rust, and corrosion in fresh and saltwater conditions.

Designed by YAMAHA for marine gearcases, this 1-gallon container supplies sustained protection for gears, bearings, and seals that run at high speeds and under heavy loads. The formula meets GL-4 performance requirements and incorporates corrosion and rust inhibitors tailored to the unique challenges of marine environments. It’s suitable for most outboards up to 250 HP, excluding Yamaha 4.2L V6 models, and is ideal for routine maintenance and oil changes before storage or heavy use.

How does this gearcase lube protect lower unit components?

The lubricant creates a durable film that reduces metal-to-metal contact under pressure, helping minimize wear on gears and bearings during prolonged high-speed operation. Rust and corrosion inhibitors shield exposed surfaces from saltwater and humidity, extending component life without compromising seals.

• High-pressure film reduces gear and bearing wear.
• Rust inhibitors prevent corrosion in saltwater environments.
• Formulated to maintain seal compatibility and prevent leaks.

Which engines and conditions is this oil appropriate for?

Use this SAE 90 (80W-90) GL-4 oil in most outboard lower units rated 250 HP or less. It’s engineered for frequent high-speed runs and extended operation in both fresh and saltwater, but it is not recommended for Yamaha 4.2L V6 outboards.

• Compatible with outboards up to 250 HP (except 4.2L V6 Yamaha).
• Suitable for fresh and saltwater boating conditions.
• Recommended for heavy-load, high-speed marine use.

How should I use and store the 1-gallon container?

Replace lower unit oil according to your boat manufacturer’s schedule or after water intrusion or long storage. Pour carefully with a fluid transfer pump or spout to avoid spills, and store the sealed container upright in a cool, dry place away from direct sunlight and extreme temperatures.

• Use a pump or funnel for clean, spill-free filling.
• Dispose of used oil following local environmental regulations.
• Store sealed, upright, in a cool, dry area away from heat sources.

What technical specifications and approvals does this product meet?

This Yamalube formulation meets SAE 90 (80W-90) viscosity and is compliant with GL-4 gear oil performance standards. It combines lubricant base stocks and additives optimized for marine gearcases to balance protection, seal compatibility, and thermal stability during extended operation.

• Viscosity: SAE 90 / 80W-90 characteristics for gear protection.
• Performance: Meets GL-4 gear oil requirements.
• Features: Built-in corrosion and rust inhibitors for marine use.

Who this product is for: Boaters, marine mechanics, and service shops that maintain outboard lower units up to 250 HP will benefit from Yamalube Marine Lower Unit Gearcase Lube. It’s aimed at owners who need reliable, manufacturer-aligned protection for gears and bearings in both salt and fresh water, especially for frequent high-speed use or seasonal maintenance. If you operate a Yamaha 4.2L V6 outboard, consult your manual for the specified lubricant.