2003 GMC Sonoma Owner's Manual - Page 293

Add coolant mixture at the recovery tank, but be careful not to spill it. Radiator Pressure Cap Yo, >an be burnec _. yo, 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. Occasionally check the coolant level in the radiator. For information on how to add coolant to the radiator, see Cooling System on page 5-33. Notice: Your radiator pressure cap is a 15 psi (105 kPa) pressure-type cap and must be tightly installed to prevent coolant loss and possible engine damage from overheating.Be sure the arrows on the cap line up with the overflow tube on the radiato filler neck. Engine Overheating You will find a coolant temperature gage on your vehicle's instrument panel. See Engine Coolant Temperature Gage on page 3-33. 5-30