1998 Lexus GS 400 Owners Manual - Page 390

ENGINE CAUTION To prevent burning yourself, do not remove the radiator cap when the engine is hot. Engine coolant selection Your coolant must contain ethylene-glycol antifreeze. In addition to preventing freezing and subsequent damage to the engine, this will also prevent corrosion. Further supplemental inhibitors or additives are neither needed nor recommended. Read the antifreeze container for information on freeze protection. Follow the manufacturer's directions for how much to mix with water. The total capacity of the cooling system is given on page 362. We recommend 50% solution be used for your Lexus, or a sufficient quantity to provide protection to about -35_C (-31_F). SPARK PLUGS GS400 Your engine is fitted with iridium-tipped spark plugs. NOTICE Use only iridium-tipped spark plugs for your engine performance and smooth drivability. GS300 NOTICE Do not use alcohol type antifreeze or plain water alone. 62G008 Your engine is fitted with twin ground electrode spark 377 plugs. NOTICE Use only twin ground electrode spark plugs for your engine performance.