2003 Mercedes ML-Class Owner's Manual - Page 288

Technical data Fuels, coolants, lubricants etc. The coolant solution must be used year round to provide the necessary corrosion protection and increase in boil-over protection. You should have it replaced every 3 years. To provide important corrosion protection, the solution must be at least 45% anticorrosion/antifreeze (equivalent to freeze protection to approx. - 22°F [-30°C]). If you use a solution that is more than 55% anticorrosion/antifreeze (freeze protection to approx. - 49°F [-45°C]), the engine temperature will increase due to the lower heat transfer capability of the solution. Therefore, do not use more than this amount of anticorrosion/antifreeze. If the coolant level is low, water and MB anticorrosion/antifreeze should be used to bring it up to the proper level (have cooling system checked for signs of leakage). Please make sure that the mixture is in accordance with label instructions. The water in the cooling system must meet minimum requirements, which are usually satisfied by normal drinking water. If you are not sure about the water quality, consult your authorized Mercedes-Benz Light Truck Center. Anticorrosion/antifreeze Your vehicle contains a number of aluminum parts. The use of aluminum components in motor vehicle engines necessitates that anticorrosion/antifreeze coolant used in such engines be specifically formulated to protect the aluminum parts. (Failure to use such anticorrosion/antifreeze coolant will result in a significantly shortened service life.) Therefore, the following product is strongly recommended for use in your vehicle: Mercedes-Benz Anticorrosion/Antifreeze agent. Before the start of the winter season (or once a year in hot southern regions), you should have the anticorrosion/antifreeze concentration checked. The coolant is also regularly checked each time you bring your vehicle to your authorized Mercedes-Benz Light Truck Center for service. 288