2005 Mercedes SLK-Class Owner's Manual - Page 426

Technical data Fuels, coolants, lubricants, etc. In areas where carbon deposits may be encountered due to lack of availability of gasolines which contain these additives, Mercedes-Benz recommends the use of additives approved by us for use on Mercedes-Benz vehicles. Refer to the Factory Approved Service Products pamphlet for a listing of approved product(s). Follow directions on product label. Do not blend any specific fuel additives with fuel. This only results in unnecessary costs and may be harmful to engine operation. Damage or malfunction resulting from poor fuel quality or from blending additional fuel additives other than those tested and approved by us for use on Mercedes-Benz vehicles listed in the Factory Approved Service Products pamphlet are not covered by the Mercedes-Benz Limited Warranty. Coolants The engine coolant is a mixture of water and anticorrosion/antifreeze, which provides: Corrosion protection Freeze protection Boiling protection (by increasing the boiling point) The cooling system was filled at the factory with a coolant providing freeze protection to approximately -22°F (-30°C) and corrosion protection. If the antifreeze mixture is effective to -22°F (-30°C), the boiling point of the coolant in the pressurized cooling system is reached at approximately 266°F (130°C). The coolant solution must be used year round to provide the necessary corrosion protection and increase boil-over protection. Refer to Maintenance Booklet for information on replacement intervals. Coolant system design and coolant used determine the replacement interval. The replacement interval published in the Maintenance Booklet is only applicable if MB 325.0 anticorrosion/antifreeze solution or other Mercedes-Benz approved products of equal specification (see Factory Approved Service Products pamphlet) are used to renew the coolant concentration or bring it back up to the proper level. 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. 426