Amazon.com: Genuine Toyota Lexus ATF Type T-IV Automatic Transmission Fluid OEM 4 quart Type-4 ATF:
Recommended for 2002 Toyota Prius. I've tried using WS on my first generation prius for experimental purposes...didn't run so smooth. After replacing it with t-iv, it ran smoother and revs are more quiet. Don't use WS on first generation priuses....