For filling up the system you will use 7.8 liters of special Red coolant type. You may use code of motor 4G62 and volume figure of 1.8 or just tell the 1989 year of production to buy liquid. For sufficient use of Hyundai Sonata you need to use suitable antifreeze. In other way 2003 Sonata won’t be used quite long and efficiently. Don’t underestimate the importance of Hyundai’s 2.0 engine cooling system.
So better use Hyundai’s advice for servicing 2006 Sonata. Every Hyundai owner should remember that engines with code 4G62 are quite demanding. 3.0 Sonata motors of 1998 year will serve more by optimal service. Better buy 7 liters of good antifreeze in Red color.