1997 Buick Riviera Owner's Manual - Page 219

How to Add Coolant to theCoolant Recovery Tank If you haven't found a problem yet, but the coolant level isn't atFULL COLD, add a50/50mixture of clean water (preferably distilled) and DEX-COOL' (silicate-free) tank. (See "Engine antifkeeze at the coolant recovery Coolant" in the Index for more information.) With plain water the wrongmix, your engine or could get too hot butyou wouldn't get the overheat warning. Your engine could catch fire and you or otherscould be burned. Use a 50/50 mix of clean water andDEX-COOL@coolant. Adding only plain water to your cooling system can be dangerous. Plain water, or some other liquid likealcohol, can boil before the proper coolant mix will. Your vehicle'scoolant warning system is set for the proper coolant mix. CAUTION: (Continued) NOTICE: In cold weather, water canfreeze and crack the engine, radiator, heater core and other parts. Use the recommended coolant and the proper coolant mix. 5-18