It’s important to use 19 liters of coolant which has Green color. In other way 1991 600 Series won’t be used quite long and efficiently. Before choosing fluid note that engine code M120.981 and volume of 6.0 were installed to your car in 1992. Only exact type of antifreeze will suit Mercedes-Benz 600 Series cooling system. Make sure you service system at Mercedes-Benz with installed 6.0 engine correctly.
It’s obvious that every M120.980 motor needs good service as stated by Mercedes-Benz in instruction. To endure car life take only Red antifreeze and pour not more or less than 18.5 liters. It will be advantageous to follow Mercedes-Benz’s rules for 1992 600 Series service. 6.0 600 Series motors of 1991 year will serve more by optimal service.