2004 Toyota Prius Owners Manual - Page 297

If you can find no leak, have your Toyota dealer test the cap pressure and check for leaks in the cooling system. CAUTION To prevent burning yourself, do not remove the radiator cap when the engine is hot. Coolant type selection Use of improper coolants may damage your cooling system. Only use "Toyota Super Long Life Coolant" or similar high quality ethylene glycol based non−silicate, non−amine, non−nitrite, and non−borate coolant with long−life hybrid organic acid technology. (Coolant with long−life hybrid organic acid technology is a combination of low phosphates and organic acids.) For the U.S.A.-"Toyota Super Long Life Coolant" is a mixture of 50% coolant and 50% deionized water. This coolant provides protection down to about −35_C (−31_F). For Canada-"Toyota Super Long Life Coolant" is a mixture of 55% coolant and 45% deionized water. This coolant provides protection down to about −42_C (−44_F). NOTICE Do not use plain water alone. Toyota recommends "Toyota Super Long Life Coolant", which has been tested to ensure that it will not cause corrosion nor result in malfunction of your coolant system with proper usage. "Toyota Super Long Life Coolant" is formulated with long−life hybrid organic acid technology and has been specifically designed to avoid cooling system malfunction on Toyota vehicles. Please contact your Toyota dealer for further details. 285