2004 Hyundai Sonata Owner's Manual - Page 167

DO-IT-YOURSELF MAINTENANCE 6- 9 4. Turn the radiator cap counterclockwise without pressing down on it, until it stops. This relieves any pressure remaining in the cooling system. And remove the radiator cap by pushing down and turning counterclockwise. Now fill the radiator with clean demineralized or distilled water. Continue to add clean demineralized or distilled water in small quantities until the fluid level stays up in the radiator neck. 5. Start the engine, top off the radiator with water and then add coolant to the reservoir until the level is between "L" and "F". 6. Replace the radiator and reservoir caps and check to be sure the drain cocks are fully closed and not leaking. G060A02Y-AAT G060B04Y-AAT SPARK PLUGS DOHC V6 Replacing the Spark Plugs The spark plugs should be changed at the intervals specified in the vehicle maintenance schedule in Section 5 or whenever engine performance indicates they should be changed. Symptoms that suggest poor spark plug performance include engine misfiring under load, loss of fuel economy, poor acceleration, etc. When spark plugs are replaced, always use spark plugs recommended by Hyundai. The use of other spark plugs can result in loss of performance, radio interference or engine damage. 1.0~1.1 mm 1.0~1.1 mm NOTE: HSM392 ! WARNING: The cooling fan is controlled by engine coolant temperature and may sometimes operate even when the engine is not running. Use extreme caution when working near the blades of the coolant fan so that you are not injured by a rotating fan blade. As the engine coolant temperature decreases, the fan will automatically shut off. This is a normal condition. Your engine was originally equipped with platinum-tipped spark plugs. Platinum-tipped spark plugs will last longer than conventional type spark plugs and can be identified by blue lines on the ceramic shell. When replacing the spark plugs, always use the genuine parts recommended. Recommended Spark Plugs: Type RN10PYP4 (CHAMPION) PGR5C-11 (NGK) RC10PYB4 (CHAMPION) PFR5N-11 (NGK) Remark For 2.4L only For 2.7L only NOTE: Do not clean or regap platinum-tipped spark plugs.