Royal Purple Max Gear 75W-90 Synthetic Gear Oil, 1 Quart — Full‑Synthetic GL‑5/GL‑4 with Synerlec

Royal Purple Max Gear 75W-90 is a high-performance synthetic gear oil formulated to protect heavily loaded gears, reduce noise and heat, and extend component life.

Max Gear 75W-90 (SKU 01300) is a premium full-synthetic gear lubricant engineered for demanding automotive, truck, RV, and marine lower-gear applications. Blending advanced synthetic base stocks with Royal Purple’s Synerlec additive technology, this GL-5/GL-4-rated fluid is designed to stand up to heavy loads, hypoid gear pressure, and repeated thermal cycling. It’s suitable for differentials, manual transmissions and lower marine gear units where a 75W-90 viscosity with hypoid friction modifiers is specified.

How does this oil protect gears under heavy load?

Max Gear 75W-90 creates a durable lubricating film that reduces metal-to-metal contact under extreme pressure. The Synerlec additive package enhances film strength and reduces wear, helping gears resist scoring and pitting during high-torque operation.

• High-quality synthetic base stocks provide stable viscosity at temperature extremes.
• Synerlec friction modifier improves load-carrying capability and surface protection.
• Formulated to resist thermal breakdown and maintain film under shock loads.

Will it make gears run quieter and cooler?

Yes — this formulation reduces friction and minimizes heat generation in gear sets, resulting in smoother operation and less noise. Lower operating temperatures also slow oil oxidation and extend service life.

• Friction-reducing additives help quiet whining and chatter in differentials.
• Improved thermal stability keeps viscosity consistent at elevated temperatures.
• Reduced metal wear means fewer sources of mechanical noise over time.

Where should I use Royal Purple Max Gear 75W-90?

Use this product in automotive and light commercial applications that call for API GL-5 or GL-4 gear oils with a 75W-90 viscosity. It’s suitable for rear and front differentials, manual transmissions, and lower marine gear units that require hypoid friction modifiers.

• Rear and front differentials in cars, trucks, and SUVs.
• Manual transmissions specifying GL-4/GL-5 75W-90 fluids.
• Lower gear units on marine engines where GL-5/GL-4 is permitted.

Do I need to add extra additives or change service intervals?

No additional additives are required; Max Gear is fully formulated with Royal Purple’s Synerlec package. For best results, follow your vehicle manufacturer’s service recommendations and oil-change intervals in the owner’s manual.

• Ready-to-use formulation — do not mix with aftermarket friction modifiers unless specified.
• Follow OEM service intervals for drain and fill procedures.
• Compatible with many conventional and synthetic gear oils, but check compatibility before mixing.

Who is this for: Royal Purple Max Gear 75W-90 is intended for mechanics, fleet managers, RV owners, marine technicians, and performance-minded drivers who need a tough, long-lasting synthetic gear oil for heavily loaded gear sets. If you want improved gear protection, quieter operation, and enhanced thermal stability in differential and manual-transmission applications that require a 75W-90 GL-5/GL-4 fluid, this product is a practical upgrade over conventional gear oils.