The Toyota Genuine ATF Type T‑IV (4 L) is a fully synthetic, low-viscosity automatic transmission fluid (part number 08886‑01705) developed by Toyota for use in vehicles equipped with AISIN‑Warner slip‑controlled automatic transmissions—covering many Toyota, Lexus, Scion, and Daihatsu models produced post‑1993. This fluid replaces earlier generations (T, T‑II, T‑III), maintaining precise friction characteristics for smooth gear shifts, optimal torque converter operation, and consistent hydraulic control. It provides excellent protection against wear, oxidation, rust, and foaming, helping prolong transmission life and preserve shift quality.

Users and technicians often report that Toyota T-IV offers long-lasting performance, with some vehicles achieving over 60,000 miles on original fill before shifts start to feel sluggish. While several reputable aftermarket fluids (like Mobil 1 or Castrol Multi‑Vehicle) also meet T‑IV or JWS 3309 specifications, genuine Toyota T-IV ensures complete OEM compatibility—helpful for warranty concerns and maintaining shift precision. It's recommended for regular drain-and-refill intervals (~30,000 mi) to preserve optimal transmission performance without requiring a full flush.