305 Operation
At the gas station
Remove the SmartKey from the starter
switch.
Open fuel filler flap by pushing at point
indicated by arrow1.
The fuel filler flap springs open.
Turn fuel filler cap counterclockwise
and hold on to it until possible pressure
is released.
Take off fuel filler cap and set it in di-
rection of arrow2 in the recess on the
inside of 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 up or over-
fill.
Replace the fuel filler cap by turning it
clockwise until it audibly engages.
Close the fuel filler flap.
Check regularly and before a long tripEngine compartment (SLK 350, example)1Windshield washer system and head-
lamp cleaning system* reservoir
2Brake fluid reservoir
3Coolant expansion tank
Warning!
G
Overfilling of the fuel tank may create pres-
sure in the system which could cause a gas
discharge. This could cause the gas to spray
back out when removing the fuel pump noz-
zle, which could cause personal injury.iLeaving the engine running and the fuel
cap open can cause the yellow fuel
tank reserve warning lamp to flash and
the ?malfunction indicator lamp
(USA only) or the ±malfunction in-
dicator lamp (Canada only) to illumi-
nate.
For more information, see “Practical
hints” (
page 364).
iFor opening the hood, see “Hood”
(page 307).
306 OperationAt the gas stationWindshield washer system and head-
lamp cleaning system*
For information on refilling the reservoir,
see “Windshield washer system and head-
lamp cleaning system*” (
page 315).
Brake fluid
For information on brake fluid, see “Fuels,
coolants, lubricants, etc.” (page 449).Coolant
For normal replenishing, use water (pota-
ble water quality).
For more information on coolant, see
“Coolant” (
page 313) and “Fuels, cool-
ants, lubricants, etc.” (
page 449).
Engine oil level
For information on engine oil, see “Engine
oil” (
page 308).Vehicle lighting
Check function and cleanliness.
For more information on vehicle lighting,
see “Replacing bulbs” (
page 400).
For information on switching on the exteri-
or lighting, see “Exterior lamp switch”
(
page 110).
Tire inflation pressure
For information on tire inflation pressure,
see “Important notes on tire inflation
pressure” (
page 328).
!If you find that the brake fluid in the
brake fluid reservoir has fallen to the
minimum mark or below, have the
brake system checked for brake pad
thickness and leaks immediately. Noti-
fy an authorized Mercedes-Benz Center
immediately. Do not add brake fluid as
this will not solve the problem.
For more information, see “Practical
hints” (
page 363).
308 OperationEngine compartment
Closing
Let the hood drop from a height of
approximately 1 ft (30 cm).
The hood will lock audibly.
Check to make sure the hood is fully
closed.
If you can raise the hood at a point
above the headlamps, then it is not
properly closed. Open it again and let it
drop with somewhat greater force.
Engine oil
The amount of oil your engine needs will
depend on a number of factors, including
driving style. Higher oil consumption can
occur when
the vehicle is new
the vehicle is driven frequently at
higher engine speeds
Engine oil consumption checks should only
be made after the vehicle break-in period.
Warning!
G
If you see flames or smoke coming from the
engine compartment, or if the coolant tem-
perature display in the multifunction display
indicates that the engine is overheated, do
not open the hood. Move away from vehicle
and do not open the hood until the engine
has cooled down. If necessary, call the fire
department.Warning!
G
The engine is equipped with a transistorized
ignition system. Because of the high voltage
it is dangerous to touch any components
(ignition coils, spark plug sockets, diagnos-
tic socket) of the ignition system
with the engine running
while starting the engine
if ignition is “on” and the engine is
turned manually
Warning!
G
Be careful that you do not close the hood on
anyone.
iDo not use any special lubricant addi-
tives, as these may damage the drive
assemblies. Using special additives not
approved by Mercedes-Benz may
cause damage not covered by the
Mercedes-Benz Limited Warranty.
More information on this subject is
available at any authorized
Mercedes-Benz Center.
309 Operation
Engine compartment
Checking engine oil level with the
control system (SLK 55 AMG only)
When checking the oil level
the vehicle must be parked on level
ground.
with the engine at operating tempera-
ture, the vehicle must have been sta-
tionary for at least 5 minutes with the
engine turned off.
with the engine not at operating tem-
perature, the vehicle must have been
stationary for at least 30 minutes with
the engine turned off.
To check the engine oil level via the
multifunction display, do the following:
Switch on the ignition (
page 36).
The standard display appears in the
multifunction display (
page 128).
Press buttonk orj on the mul-
tifunction steering wheel repeatedly
until the following message appears in
the multifunction display (
page 124):
One of the following messages will
subsequently appear in the multifunc-
tion display:
Engine oil level
ok
Add 1.0 qt.
(Canada:
1.0 liter
)
to reach max. oil level
Add 1.5 qts.
(Canada:
1.5 liters
)
to reach max. oil level
Add 2.0 qts.
(Canada:
2.0 liters
)
to reach max. oil level
If necessary, add engine oil.
For adding engine oil, see “Adding en-
gine oil” (
page 312).
For more information on engine oil, see
“Fuels, coolants, lubricants, etc.”
(
page 449).iIf you want to interrupt the checking
procedure, press buttonk orj
on the multifunction steering wheel
(page 124).
311 Operation
Engine compartment
Checking engine oil level with the oil
dipstick (SLK 280, SLK 350 only)
When checking the oil level
the vehicle must be parked on level
ground.
with the engine at operating tempera-
ture, the vehicle must have been sta-
tionary for at least 5 minutes with the
engine turned off.
with the engine not at operating tem-
perature, the vehicle must have been
stationary for at least 30 minutes with
the engine turned off.1Oil dipstick
2Upper (max) mark
3Lower (min) mark
To check the engine oil level with the oil
dipstick, do the following:
Open the hood (
page 307).
Pull out oil dipstick1.
Wipe oil dipstick1 clean.
Fully insert oil dipstick1 into the
dipstick guide tube.
Pull out oil dipstick1 again after
approximately 3 seconds to obtain ac-
curate reading.
The oil level is correct when it is be-
tween the lower (min) mark3 and
upper (max) mark2 of oil dipstick1.
If necessary, add engine oil.
For adding engine oil, see “Adding en-
gine oil” (
page 312).
For more information on engine oil, see
“Fuels, coolants, lubricants, etc.”
(
page 449).
For more information on messages in the
multifunction display concerning engine
oil, see the “Practical hints” section
(page 368).iThe filling quantity between the upper
and lower marks on the oil dipstick is
approximately 2.1 US qt. (2.0 l).
313 Operation
Engine compartment
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. To check
the coolant level, the vehicle must be
parked on level ground and the engine
must be cool.Warning!
G
In order to avoid any possibly 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 ½ turn to relieve excess pres-
sure. If opened immediately, scalding
hot fluid and steam will be blown out un-
der 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.
314 OperationEngine compartmentThe coolant expansion tank is located on
the passenger side of the engine compart-
ment.SLK 350 (example)1Coolant expansion tank
2Cap
3Marking bar in the expansion tank
Using a rag, turn cap2 slowly approx-
imately one half turn counterclockwise
to release any excess pressure.
Continue turning cap2 counterclock-
wise and remove it.
The coolant level is correct if the level
for cold coolant: reaches marking
bar3 in expansion tank1
for warm coolant: is approximately
0.6 in (1.5 cm) higher
Add coolant as required.
Replace and tighten cap2.
For more information on coolant, see
“Coolants” (
page 453).
Battery
Your vehicle’s battery is located in the en-
gine compartment.
The battery should always be sufficiently
charged in order to achieve its rated ser-
vice life. Refer to the Maintenance Booklet
for battery maintenance intervals.
If you use your vehicle mostly for
short-distance trips, you will need to
have the battery charge checked more
frequently.
When replacing the battery, always use
batteries approved by Mercedes-Benz.
If you do not intend to operate your vehicle
for an extended period of time, consult an
authorized Mercedes-Benz Center about
steps you need to observe.
344 OperationTires and wheelsTire and loading terminology
Accessory weight
The combined weight (in excess of those
standard items which may be replaced) of
automatic transmission, power steering,
power brakes, power windows, power
seats, radio, and heater, to the extent that
these items are available as
factory-installed equipment (whether
installed or not).
Air pressure
The amount of air inside the tire pressing
outward on each square inch of the tire.
Air pressure is expressed in pounds per
square inch (psi), or kilopascal (kPa), or
bars.
Aspect ratio
Dimensional relationship between tire
section height and section width
expressed in percentage.Bar
Another metric unit for air pressure. There
are 14.5038 pounds per square inch (psi)
to 1 bar; there are 100 kilopascals (kPa)
to 1 bar.
Bead
The tire bead contains steel wires wrapped
by steel cords that hold the tire onto the
rim.
Cold tire inflation pressure
Tire inflation pressure when your vehicle
has been sitting for at least three hours or
driven no more than one mile (1.6 km).
Curb weight
The weight of a motor vehicle with stan-
dard equipment including the maximum
capacity of fuel, oil, and coolant, and, if so
equipped, air conditioning and additional
optional equipment, but without passen-
gers and cargo.DOT (D
epartment o
f T
ransportation)
A tire branding symbol which denotes the
tire meets requirements of the
U.S. Department of Transportation.
GAWR (G
ross A
xle W
eight R
ating)
The GAWR is the maximum permissible
axle weight. The gross vehicle weight on
each axle must never exceed the GAWR for
the front and rear axle indicated on the
certification label located on the driver’s
door B-pillar.
GVW (G
ross V
ehicle W
eight)
The GVW comprises the weight of the
vehicle including fuel, tools, spare wheel,
installed accessories, passengers and
cargo and, if applicable, trailer tongue
load. The GWV must never exceed the
GWVR indicated on the certification label
located on the driver’s door B-pillar.