2011 Mercedes C-Class Owner's Manual - Page 309

Service products and capacities into contact with your skin. Before refueling, extinguish all naked flames. Never allow sparks or smoking materials near ethanol. 307 Changing the fuel type For best performance and driveability, it is recommended that you use either one or the other fuel. Avoid alternating regularly between the two different types of fuel. When changing the fuel type, make sure: Rthe fuel level is below half full. Rthe fuel level is above the reserve level. This is identifiable by the fuel tank reserve warning lamp not being lit. Ryou add more than 5 gallons (20 liters) of fuel. Rbefore refueling, you switch off the engine. Rthe engine is started and operated for at least five minutes immediately after refueling. These precautions and recommendations should prevent any difficulties when starting and operating the engine which otherwise may be experienced before the engine has fully adapted to the different fuel. If, in spite of these recommendations, the engine does not perform properly, add at least 3 gallons (12 liters) of gasoline. This may improve the running of the engine. Fuel consumption Ethanol fuel (E85) contains less energy per gallon than gasoline. To ensure that the engine performance with ethanol fuel (E85) is similar to that when using gasoline, the engine must burn more ethanol fuel. As a result, it is to be expected that the fuel consumption will increase when using ethanol fuel (E85), compared to gasoline. Maintenance When you bring your vehicle for maintenance or repairs, please inform your authorized Mercedes-Benz Center if you use or have used ethanol fuel (E85). Low outside temperatures It is possible that the time required for the starting procedure will significantly increase at outside temperatures below 32 ‡ (0 †). At low outside temperatures, Mercedes-Benz recommends the use of an auxiliary heater. For further information, contact an authorized Mercedes-Benz Center. Rough idling may also be experienced at low outside temperatures until the engine is fully warmed up. Ethanol fuel (E85) is unsuitable for use when outside temperatures fall below 14 ‡ (-10 †). High outside temperatures At outside temperatures above 95 ‡ (35 †), the time required for the starting procedure may increase and be accompanied by rough idling following the start. Fuel requirements Use only premium-grade unleaded gasoline. The octane number should be at least 91. Details can be found on the gas pump. The octane number is the average value of the Research Octane Number (RON) and Motor Octane Number (MON): (RON + MON) / 2, also known as knock resistance. Reformulated Gasoline (RFG) and/or unleaded gasoline with additives can be used if the concentration of the additives in the fuel does not exceed 10%, e.g.: REthanol RTAME RETBE RIPA RTBA For MTBE, the concentration should not exceed 15%. The concentration of methanol in gasoline including other additives must not exceed 3%. Using mixtures of methanol and ethanol is not permitted. Gasohol, a mixture of 10% ethanol and 90% unleaded gasoline can be used. Z Technical data