2008 Mercedes S-Class Owner's Manual - Page 540

Operation At the gas station Take off the fuel filler cap and set it in the direction of arrow 2 and place it into holder 3 located on the inside of the fuel filler flap. To prevent fuel vapors from escaping into open air, fully insert filler nozzle unit. Only fill your tank until the filler nozzle unit cuts out - do not top off or overfill. Warning! G i Only use premium unleaded gasoline with a minimum Posted Octane Rating of 91 (average of 96 RON/86 MON). Please contact gas station personnel in case labels on the pump cannot be found. For more information on gasoline see "Premium unleaded gasoline" ( page 729), see "Fuel requirements" ( page 729) and the Factory Approved Service Products pamphlet. Overfilling of the fuel tank may create pressure in the system which could cause a gas discharge. This could cause the gas to spray back out when removing the fuel pump nozzle, which could cause personal injury. Replace the fuel cap by turning it clockwise until it audibly engages. i Leaving the engine running and the fuel cap open can cause the yellow engine malfunction indicator lamp ± to illuminate. For more information, see the "Practical hints" section ( page 602). i Make sure to close the fuel filler flap before locking your vehicle as the flap locking pin prevents closing after you have locked the vehicle. Close the fuel filler flap. You should hear the latch close shut. 539