2006 Mercedes C-Class Owner's Manual - Page 445

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 Factory Approved Service Products pamphlet for a listing of approved product(s). Follow directions on product label. Do not blend other fuel additives with fuel. This only results in unnecessary cost 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. Fuel requirements Only use premium unleaded fuel: The octane number (posted at the pump) must be 91 min. It is an average of both the Research (R) octane number and the Motor (M) octane number: (R+M)/2. This is also known as the ANTI-KNOCK INDEX. Unleaded gasoline containing oxygenates such as ethanol, IPA, IBA and TBA can be used provided the ratio of any one of these oxygenates to gasoline does not exceed 10%; MTBE must not exceed 15%. The ratio of methanol to gasoline must not exceed 3% plus additional cosolvents. Using mixtures of ethanol and methanol is not allowed. Gasohol, which contains 10% ethanol and 90% unleaded gasoline, can be used. These blends must also meet all other fuel requirements, such as resistance to spark knock, boiling range, vapor pressure, etc. 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 approx. 266°F (130°C). 444