Red Line 75W90 Synthetic Differential Gear Oil

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Red Line's full-synthetic 75W90 is Red Line's most popular gear oil and our favorite differential and general purpose 90 weight gear oil.

This oil has superior shear stability and reduced oxidation compared to other synthetics and conventional gear oils, exceeds API GL-5 specifications, and is engineered to provide the highest degree of protection and improvement of differential efficiency for better mileage, longer drain intervals, and less wear.


  • Blended with Ester: Ester is a chemically synthesized base oil that increases lubricating properties, thermal and oxidative stability, and detergency. It increases shear stability for reduced gear noise, and provides a more consistent viscosity in warm and cold temperatures
  • Extreme pressure additives: Includes extreme pressure additives which is great for slow Rock Crawling
  • High viscosity-index: Includes friction modifiers to make it compatible with a wide range of applications, including the contact angles of Ring & Pinion gears (hypoid gear mesh) and limited-slip differentials

Special Note: Due to the friction modifiers, Red Line does NOT recommend this gear oil to be used in manual transmissions. Instead, please use their synthetic oil specifically designed for transmissions that we carry here: Red Line MT-90.

Bullet points from the bottle:

  • Greatest extreme pressure protection
  • Lowest coefficient of friction
  • Reduces temperatures and improves drivetrain efficiency
  • Contains additive for limited-slip differentials
  • Supplemental friction modifier additive not required unless chatter occurs
  • Compatible with conventional and synthetic oils

Recommendations/Qualifications: API GL-5, GL-6, MT-1, MIL-L-2105E, SAE J2360 and Chrysler spec MS-9763. Suitable replacement for a differential calling for an 80W90 or SAE 90 gear oil.

Each bottle contains 1 quart (946 ml). Sold individually.

We also carry these other great Red Line Synthetics

MT-90 for Manual Transmissions

ShockProof for Heavy Duty Use

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