Page 301 of 474

300 Operation
Engine compartment
Unscrew filler cap1 from filler neck.
Add engine oil as required.
Be careful not to overfill with oil.
Be careful not to spill any oil when adding.
Avoid environmental damage caused by oil
entering the ground or water.
Screw filler cap1 back on filler neck.
For more information on engine oil, see
“Technical data” (
page 451) and
(
page 453).
Transmission fluid level*
Vehicles with automatic transmission*:
The transmission fluid level does not need
to be checked. If you notice transmission
fluid loss or gear shifting malfunctions,
have an authorized Mercedes-Benz Center
check the transmission.
Coolant level
The engine coolant is a mixture of water
and anticorrosion/antifreeze.
When checking the coolant level,
the vehicle must be parked on level
ground
the coolant temperature must be
below 158°F (70°C)
!Excess oil must be siphoned or drained off.
It could cause damage to the engine and
emission control system not covered by the
Mercedes-Benz Limited Warranty.
Warning!G
In order to avoid any potentially serious
burns:
Use extreme caution when opening the
hood if there are any signs of steam or
coolant leaking from the cooling system,
or if the coolant temperature gauge indi-
cates that the coolant is overheated.
Do not remove pressure cap on coolant
reservoir if coolant temperature is
above 158°F (70°C). Allow engine to
cool down before removing cap. The
coolant reservoir contains hot fluid and
is under pressure.
Using a rag, slowly open the cap approx-
imately 1/2turn to relieve excess pres-
sure. If opened immediately, scalding
hot fluid and steam will be blown out
under pressure.
Do not spill antifreeze on hot engine
parts. Antifreeze contains ethylene
glycol which may burn if it comes into
contact with hot engine parts.
Page 380 of 474

379 Practical hints
What to do if …
Display symbolDisplay messagePossible cause/consequencePossible solution
NEngine Oil Level
Reduce Oil LevelSLK 55 AMG only:
You have added too much engine
oil. There is a risk of damaging the
engine or the catalytic converter.Have oil siphoned or drained off.
Observe all legal requirements with respect
to its disposal.
Engine Oil Level
Stop, turn engine off.There is no oil in the engine. There
is a danger of engine damage.Stop the vehicle in a safe location or as soon
as it is safe to do so.
Turn off the engine.
Apply the parking brake (page 59).
Add engine oil (page 299) and check the
engine oil level (
page 296).
AReserve FuelThe fuel level has dropped below
the reserve mark.Refuel at the next gas station (page 291).
4Gas Cap
Is OpenA loss of pressure has been detect-
ed in the fuel system. The fuel cap
may not be closed properly or the
fuel system may be leaky.Check the fuel cap (page 291).
If it is not closed properly:
Close the fuel cap.
If it is closed properly:
Have the fuel system checked by an autho-
rized Mercedes-Benz Center.
Page 456 of 474

455 Technical data
Fuels, coolants, lubricants, etc.
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 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.
Gasoline additives
A major concern among engine manufac-
turers is carbon build-up caused by gaso-
line. Mercedes-Benz only recommends
only the use of quality gasoline containing
additives that prevent the build-up of
carbon deposits.
After an extended period of using fuels
without such additives, carbon deposits
can build up, especially on the intake
valves and in the combustion area, leading
to engine performance problems such as:
Warm-up hesitation
Unstable idle
Knocking/pinging
Misfire
Power lossIn 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
(USA only) or contact an authorized
Mercedes-Benz Center 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 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 are not
covered by the Mercedes-Benz Limited
Warranty.
Page 467 of 474

466 Index
Manual transmission 153
Driving 53
Gearshift pattern 51
Starting with SmartKey 51
Maximum inflation pressure 332
Maximum load rating 332
Maximum loaded vehicle weight 332
Mechanical key see SmartKey
Memory function* 107
Menus see Control system menus
Messages in the multifunction display see
Multifunction display messages
Mirror lamp* see Sun visors
Mirrors 168
Additional turn signals 401
Adjusting 46
Antiglare position 168
Auto-dimming* 168
Exterior rear view mirrors 46
Interior rear view mirror 46
Mobile phone see Telephone*
MOE tires* see MOExtended system*
MOExtended system* 321, 421
MON 292, 455Motor Octane Number see MON
MP3 210
Multifunction display 121
Multifunction display messages 360
ABS 362
Air bags 365–368
Battery, Vehicle 372
Brake fluid 373
Brakes 373
Bulbs 381–386
Coolant 374–376
Cruise control 362
Doors 371
Engine oil 377–379
ESP
®362, 363
Fuel 379
Hood 371
Low tire pressure 387
Maintenance service indicator 337
Parking brake 372
Passenger front air bag 367
Retractable hardtop 380, 388
Run Flat Indicator* 369
SmartKey 381SRS 364
Symbol messages 371
Telephone* 388
Text messages 362
Tire Pressure Monitoring System 370
Transmission 364
Trunk lid 371
Vehicle status message memory 135
Washer fluid 388
Multifunction steering wheel 28, 122
Heating* 276
N
Navigation system* 135
Neck-level heating see AIRSCARF*
Neutral gear position
Automatic transmission* 155, 157
Manual transmission 154
Night security illumination (Control
system) 144
Normal occupant weight 332
Number, Vehicle Identification (VIN) 438