ULTRA 1PLUS 75W-90 Full Synthetic Gear Oil SAE 75W-90 GL-4 — 3-Quart jug, low-temp flow & high-load protection

Engineered from premium synthetic base stocks and advanced anti-scuff additives, this 75W-90 GL-4 gear oil meets SAE J306 viscosity and API GL-4 performance levels. It delivers consistent low-temperature flow for easier shifting, strong film strength under high torque, and enhanced resistance to oxidation, rust, and foaming. Packaged as a 3-quart jug for service and topping applications, it’s intended for passenger cars and light trucks that specify GL-4 or where friction characteristics must be maintained for synchronizers and limited-slip setups.

How does this gear oil improve shifting and drivetrain feel?

ULTRA 1PLUS 75W-90 uses friction modifiers and refined synthetic basestocks to balance smooth synchronizer engagement with gear protection. That reduces gear grinding and provides consistent shift feel across temperature ranges without compromising wear resistance.

• Stable low-temperature viscosity for quicker oil flow at cold starts
• Friction modifiers tuned for synchronizer compatibility
• Strong film strength under high torque to prevent metal-to-metal contact
• Minimizes gear noise and rough engagement

What protection does it offer under heavy load or high heat?

Designed for extreme-pressure applications, this GL-4 formula forms a resilient lubrication film that resists scuffing and wear even under repeated high-load conditions. Thermal and oxidation stability keep the lubricant effective longer, reducing varnish, deposits, and frequent service intervals.

• Advanced anti-scuff additives for high-load protection
• Superior oxidation resistance to limit viscosity breakdown
• Anti-foam and rust inhibitors for cleaner internals
• Extends gear and bearing life under sustained stress

Is this oil compatible with limited-slip differentials and synchronizers?

Yes — the formula includes friction modifiers that maintain the correct shear characteristics for limited-slip differentials while remaining GL-4 compliant for synchronizer-friendly performance. It’s a cost-effective option where GL-4 chemistry is specified.

• Limited-slip compatible friction profile
• API GL-4 certification ensures safe synchronizer operation
• Suitable for many manual transmissions and transaxles
• Reduces the need for separate additives in most applications

How do I know when to use ULTRA 1PLUS 75W-90 in my vehicle?

Check your owner’s manual or service guide for API GL-4 or SAE 75W-90 recommendations. This product fits passenger cars and light trucks calling for GL-4 performance, particularly where smoother shifting and limited-slip compatibility are desired.

• Follow manufacturer viscosity and GL-4 specifications
• Ideal for manual transmissions, transaxles, and differentials
• Comes in a 3-quart jug suitable for top-offs or light service work
• Not intended to replace GL-5 when GL-5 is explicitly required

This ULTRA 1PLUS SAE 75W-90 Full Synthetic Gear Oil balances all-season flow, high-temperature durability, and friction characteristics needed for modern gearboxes. It focuses on protecting gears, synchronizers, and bearings while reducing maintenance overhead through better thermal and oxidation resistance.

Who is this for? Mechanics, DIY enthusiasts, and fleet operators who require an API GL-4 rated gear lubricant for passenger cars and light trucks will find this product appropriate. It’s particularly useful when the service specification calls for 75W-90 viscosity with synchronizer-friendly friction behavior or when limited-slip performance must be preserved. Always confirm compatibility with your vehicle’s service manual before use.