1998 GMC Sonoma Owner's Manual - Page 228

I NOTICE: In cold weather, water can freeze and crack the engine, radiator, heater core and other parts. Use the recommended coolant and the proper coolant mixture. I ' A CAUTION: You can be burnedif you spill coolant on hot engine parts. Coolant contains ethylene glycol and it will burn if the engine parts are hot enough. Don't spill coolant on a hot engine. When the coolant in the coolant recovery tank is at the ADD mark, start your vehicle. If the overheat warning continues, there's one more thing you can try. You can add the proper coolant mixture directly to the radiator, but be sure the cooling system is cool before you do it. 5-16