2008 Mercedes CLK-Class Owner's Manual - Page 493

Technical data Fuels, coolants, lubricants, etc. Premium unleaded gasoline Warning! G ! To maintain the engine's durability and performance, premium unleaded gasoline must be used. If premium unleaded gasoline is not available and low octane fuel is used, follow these precautions: Have the fuel tank only partially filled with unleaded regular gasoline and fill up with premium unleaded gasoline as soon as possible. Avoid full throttle driving and abrupt acceleration. Do not exceed an engine speed of 3000 rpm if the vehicle is loaded with a light load such as two persons and no luggage. Do not exceed 2/3 of maximum accelerator pedal position if the vehicle is fully loaded or operating in mountainous terrain. 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 Octane Number (RON) and the Motor Octane Number (MON): (RON+MON)/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 not to exceed 15%. The ratio of methanol to gasoline must not exceed 3% plus additional co-solvents. 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. Gasoline is highly flammable and poisonous. It burns violently and can cause serious personal injury. Never allow sparks, flame or smoking materials near gasoline! Turn off the engine before refueling Whenever you are around gasoline, avoid inhaling fumes and skin or clothing contact, extinguish all smoking materials. Direct skin contact with fuels and the inhalation of fuel vapors can damage your health. 492