Royal Purple Max-Gear 75W-90 Synthetic Gear Oil 1 Quart — GL-5/GL-4, High-Performance Protection

Royal Purple Max-Gear 75W-90 is a full-synthetic, high-performance gear oil formulated to protect heavily loaded differentials and manual transmissions while improving smoothness and reducing noise.

Max-Gear blends premium synthetic base stocks with Royal Purple’s Synerlec additive technology to deliver durable lubrication for hypoid gears, manual transmissions and lower marine gear units that call for API GL-5 or GL-4 service. This 1-quart (32-ounce) bottle offers a convenient size for topping up differentials, performing maintenance on trucks, motorhomes, or cars, and for DIYers or professional shops that need a reliable, high-quality gear lubricant.

How does Max-Gear 75W-90 protect heavily loaded gears?

Max-Gear is engineered to form a resilient lubricating film that resists shearing and protects gear teeth under high pressure. The Synerlec additive package reduces metal-to-metal contact, helping gears run cooler and extending component life without requiring additional aftermarket additives.

• Formulated with high-quality synthetic base oils for thermal stability
• Synerlec additive technology enhances wear protection
• Hypoid friction modifiers included for clutch and cone-type differentials
• Rated for API GL-5/GL-4 applications

Will this oil work in my differential or manual transmission?

Use Max-Gear wherever the vehicle manufacturer specifies an API GL-5 or GL-4 gear oil and permits 75W-90 viscosity. It’s suitable for front and rear differentials, manual transmissions, and lower marine gears that accept GL-5/GL-4 fluids, so always check your owner’s manual for compatibility first.

• Recommended for truck, RV/motorhome, passenger car differentials
• Approved for manual transmissions requiring hypoid friction modifiers
• Compatible with many lower marine gear units specifying GL-5/GL-4
• No extra friction modifiers or aftermarket additives needed

What performance benefits will I notice after switching to Max-Gear?

Owners commonly report smoother gear changes, quieter operation, and lower running temperatures after switching to a high-quality synthetic gear oil like Max-Gear. Because it resists breakdown under stress, it can help maintain gear efficiency and reduce the frequency of service interventions.

• Quieter differential and transmission operation
• Improved thermal and oxidative stability under load
• Reduced wear and prolonged component life
• Maintains performance without additional additives

How should I use and store this 1-quart bottle?

The 32-ounce package is ideal for top-ups or smaller gearboxes; always follow your vehicle manufacturer’s recommended service intervals and fill procedures. Store the bottle upright in a cool, dry place away from direct sunlight and extreme temperatures to preserve additive effectiveness.

• Use for topping off or small service jobs
• Follow vehicle owner’s manual for fill levels and procedures
• Keep tightly sealed and stored in a cool, dry environment
• Dispose of used oil and containers per local regulations

Who is this for? Royal Purple Max-Gear 75W-90 is aimed at vehicle owners and mechanics who need a robust synthetic gear oil for heavily loaded gear sets—owners of trucks, motorhomes, performance cars, and boats with lower gear units will benefit most. It’s also suitable for DIY enthusiasts and repair shops seeking a single product that covers many GL-5/GL-4 applications without extra additives. For best results, confirm viscosity and API requirements in your equipment manual before use.