The Toyota Genuine WS Automatic Transmission Fluid (4 L) is a fully synthetic, low-viscosity fluid specifically engineered for Toyota and Lexus automatic transmissions from 2004 onward. It meets the stringent JWS 3324 “World Standard” specification, designed for smooth shifting, optimal hydraulic pressure control under hot conditions, and enhanced fuel efficiency. The fluid’s superior low-temperature flow improves cold-weather shift quality, while its advanced additive package protects internal parts from wear, oxidation, and deposit build-up—helping extend transmission life and performance reliability.

Owners frequently report noticeably smoother shifts and improved drivability after WS fluid changes, especially compared to older or aftermarket alternatives. Many technicians recommend fresh WS fluid during maintenance intervals, noting it helps transmission systems maintain their original factory feel. While some users explore high-end substitutes like Amsoil or Redline, Toyota continues to recommend genuine WS for compatibility and warranty compliance .