ULTRA 1PLUS 75W-90 Full Synthetic Gear Oil 3-Quart, API GL-4 Year-Round Protection

ULTRA 1PLUS SAE 75W-90 Full Synthetic Gear Oil is a premium API GL-4 gear lubricant formulated to protect manual transmissions, transaxles, and differentials across all seasons.

This full synthetic 75W-90 gear oil blends advanced base stocks with anti-scuff additives and friction modifiers to deliver consistent protection under heavy loads and wide temperature swings. Engineered to meet or exceed API GL-4 and SAE J306 specifications, it supports smooth shifting, limits wear on gears and synchronizers, and helps extend component life while resisting oxidation and deposit formation.

How does this gear oil perform in cold starts and high heat?

ULTRA 1PLUS 75W-90 is designed for year-round performance: it flows at low temperatures for reliable lubrication during cold starts and keeps a stable film at high operating temperatures. The synthetic base oils reduce viscosity breakdown so the gear surfaces remain protected under sustained heat.

• Meets SAE J306 low- and high-temperature requirements for consistent viscosity.
• Fast low-temperature flow to protect gears at startup.
• High thermal stability prevents viscosity loss under heavy loads.
• Resists oxidation to reduce varnish and sludge build-up.

Will this oil reduce wear and maintenance needs?

The formula creates a strong, stable lubricant film that lowers metal-to-metal contact, reducing wear on gear teeth, bearings, and synchronizers. With improved protection and cleaner operation, service intervals can be more predictable and component replacement less frequent.

• Advanced anti-scuff chemistry minimizes micro-pitting and abrasion.
• Friction modifiers support smooth synchronizer engagement.
• Limits deposit formation for cleaner internals and less maintenance.
• Designed to protect gears under high torque and shock loading.

Is this compatible with limited-slip differentials and common drivetrains?

Yes—ULTRA 1PLUS 75W-90 includes friction-modifying technology suitable for many limited-slip differentials while meeting API GL-4 service requirements for manual transmissions and transaxles. Always check vehicle manufacturer recommendations for specific additive compatibility.

• API GL-4 certified for manual transmissions and transaxles.
• Friction modifiers to support limited-slip function where specified.
• Appropriate for passenger cars and light trucks using GL-4 oils.
• Not a substitute for gear oils requiring GL-5 or special OEM fluids unless approved.

How does the oil protect against corrosion, foaming, and oxidation?

The additive package contains rust inhibitors, anti-foam agents, and antioxidants that preserve lubricant integrity and cleanliness. This helps the oil maintain full film strength and prevents issues that can lead to premature wear or reduced performance.

• Oxidation inhibitors slow thermal breakdown and acid formation.
• Rust and corrosion inhibitors protect metal surfaces in wet conditions.
• Anti-foam additives ensure stable film under aeration and agitation.
• Helps maintain clean gear surfaces, lowering deposit-related wear.

Who is this for? ULTRA 1PLUS SAE 75W-90 Full Synthetic Gear Oil is aimed at drivers and mechanics seeking robust, year-round protection for manual transmissions, transaxles, and light-duty differentials. It benefits owners of passenger cars and light trucks who want improved gear life, smoother shifting, and resistance to heat and oxidation. For vehicles specifying GL-4 service and 75W-90 viscosity, this product is a cost-effective, high-performance choice—always verify manufacturer fluid requirements before use.