Royal Purple Max Gear 75W-90 Gear Oil — 6-Quart Case (1 Pack), Synthetic GL-5/GL-4 with Synerlec Protection

Royal Purple Max Gear 75W-90 is a high-performance hypoid gear oil engineered to protect heavily loaded differentials, manual transmissions and lower marine gear units while improving smoothness and reducing wear.

Designed for vehicles and equipment that require API GL-5 or GL-4 lubrication, this 6-quart case (part number 06300) blends premium synthetic base stocks with Royal Purple’s Synerlec additive technology. The formula is non-corrosive to yellow metals and is safe for synchronizers, delivering extended gear life, quieter operation and lower operating temperatures compared with conventional gear oils.

How does Max Gear protect heavily loaded gears?

Max Gear uses a tough synthetic formulation combined with friction-modifying additives to form a durable film on gear surfaces. This film resists metal-to-metal contact under extreme pressure, reducing wear and helping bearings and gear teeth last longer.

• High pressure film strength for hypoid and spiral bevel gears
• Synerlec additive package to reduce wear and scuffing
• Lower operating temperatures for prolonged component life

Can I use this oil in differentials, transmissions and marine lower units?

Yes — Max Gear is recommended for front and rear differentials, manual transmissions and marine lower gear units that call for API GL-5 or GL-4 fluids. It’s formulated to be non-corrosive to brass, bronze and copper, making it safe where yellow metals are present.

• API GL-5 and GL-4 compliant for wide equipment compatibility
• Non-corrosive to soft metals—protects bushings and bearings
• Synchronizer-safe for manual transmission applications

Will using Max Gear affect driveline efficiency or noise?

Royal Purple’s friction modifier and Synerlec technology help reduce drivetrain drag and dampen gear noise, resulting in smoother, quieter operation. Lower drag can also contribute to more consistent power delivery in 4x4 and heavy-duty vehicles.

• Friction modifier to reduce drivetrain resistance
• Improved smoothness and reduced gear whine under load
• Helps maintain power transfer efficiency across drivetrain components

What maintenance benefits can I expect from switching to Max Gear?

Switching to this advanced synthetic gear oil can extend service intervals by limiting wear, reducing corrosion and keeping operating temperatures lower. The result is fewer repairs and longer life for gearboxes, differentials and bearings when compared with many conventional oils.

• Extended gear and bearing life versus standard gear oils
• Corrosion protection for mixed-metal environments
• No need for extra additives—formulated as a complete protector

Who is this for: Royal Purple Max Gear 75W-90 is aimed at truck owners, off-road and 4x4 enthusiasts, fleet operators and marine owners who need a robust, multi-application gear lubricant. If your vehicle or equipment specifies API GL-5 or GL-4 and you want improved wear protection, quieter operation and longer component life from a single product, this 6-quart case is a practical choice for service intervals or multiple-vehicle maintenance.