Mercury High Performance Gear Lube is an exclusive formulation engineered to provide maximum protection and extended gear life in extreme conditions including high speed and high horsepower applications.

What this is: OEM SAE 90 High Performance gear lube for high-speed / high-hp gearcases.
Where it’s used: Most Mercury, Mariner, Force outboards, jet pumps/Sport Jet 75+, and MerCruiser sterndrives.
Service cadence: Change annually or ~100 hrs (≈ 50 hrs in saltwater), and before storage.
You’ll also need: Gear lube pump (fits drain port) + 2 new drain screw gaskets.

Why this formula

• Extreme-load protection – engineered for high torque / high RPM gearsets.
• Shear-stable film – maintains viscosity under heat to protect gears & bearings.
• Water intrusion defense – helps guard against corrosion if trace moisture enters the case.
• OEM-tested – blended to Mercury tolerances for seal compatibility and anti-foaming.

How much do I need?

Always check your owner’s manual or schematics for capacity. As a rule of thumb, smaller outboards often use under a quart, while mid-size outboards and sterndrives often need ~1 quart or a bit more. When in doubt, buy two—an opened spare is handy for mid-season top-offs.

Clean change checklist

1. Warm the gearcase briefly.
2. Remove lower drain screw, then upper vent screw; drain fully.
3. Pump new lube from the lower port until it flows from the upper vent.
4. Install new gaskets, reinstall upper, then lower screws; wipe & check.

(Tip: milky lube = water; investigate seals before running again.)

This Mercury High Performance Gear Lube is intended for use in all Mercury, Mariner, and Force Outboard lower units, jet pumps, Sport Jets 75HP and above, and all Mercury MerCruiser sterndrives.

Mercury recommends changing your gear lube at least once per year prior to storage), after every 100 hours of operation under normal use, or after 50 hours of operation in a saltwater environment.

FAQs

Is this safe for Command Thrust (CT) gearcases?
Yes – this High Performance SAE 90 is designed for larger-prop, high-load gearcases like CT when specified by Mercury.

Can I mix with other marine gear lubes?
For best results, avoid mixing. If you’re switching brands or formulas, fully drain and refill.

Annual vs. hour-based changes – what’s more important?
Do whichever comes first. Also change before winter storage even if hours are low.

Do I need new seals every change?
Not full seals, but replace the two drain screw gaskets each service to ensure a proper seal.

• Supersessions
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