Full synthetic 75W-90 gear oil is a high-performance lubricant used primarily for manual transmissions and differentials. It offers superior wear protection, longer service life, and better thermal stability compared to standard mineral oils. While your personal records include an order for a 2013 Toyota Tacoma transmission mount, the owner's manual for that vehicle typically recommends 75W-85 for differentials, though many owners successfully use 75W-90 as a more accessible alternative.Key Specifications & PerformanceViscosity Consistency: 75W-90 maintains more consistent thickness across extreme temperatures, staying thinner in cold starts and thicker under high heat than 80W-90.GL-4 vs. GL-5 Ratings:API GL-4: Designed for manual transmissions with "yellow metal" (brass/bronze) synchronizers.API GL-5: