Castrol TranSynd 668 is a premium, full-synthetic automatic transmission fluid specifically formulated for Allison Transmission® on-highway automatic transmissions. TranSynd 668 provides oxidative stability, anti-wear performance, and friction durability, as well as TES 668�?specification differentiators such as extended anti-shudder durability and extended clutch friction durability. This fluid features an Allison TES 668 approval. The TES 668 spec is fully backwards compatible for TES 295® applications, but is not backwards compatible for TES 468�?applications. Delivers improved gear protection Delivers extended anti-shudder durability Delivers extended clutch-friction durability Allows for extended drain intervals of up to 300,000 miles or 48 months in general-duty transmissions and up to 150,000 miles or 48 months in severe-duty transmissionsnbsp; Provides excellent shear stability that provides a stable viscosity, which provides wear protection in gears throughout the drain interval Provides excellent thermal and oxidation stability resulting in lower deposit formation Provides superior high-low temperature performance due to full-synthetic base fluids Provides excellent corrosion and foaming resistance Recommended Applicator: Allison TES 668, Backwards Compatible with Allison TES 295