294 Operation
Engine compartment
Hood
Opening
1Hood lock release lever
Warning!G
Do not pull the release lever while the vehi-
cle is in motion. Otherwise the hood could
be forced open by passing air flow.
This could cause the hood to come loose
and injure you and/or others.
Warning!G
If you see flames or smoke coming from the
engine compartment, or if the coolant tem-
perature gauge indicates that the engine is
overheated, do not open the hood. Move
away from the vehicle and do not open the
hood until the engine has cooled. If neces-
sary, call the fire department.
Warning!G
You could be injured when the hood is open
– even when the engine is turned off.
Parts of the engine can become very hot. To
prevent burns, let the engine cool of com-
pletely before touching any components on
the vehicle. Comply with all relevant safety
precautions.
Warning!G
To help prevent personal injury, stay clear of
moving parts when the hood is open and the
engine is running.
The radiator fan may continue to run for
approximately 30 seconds or may even
restart after the engine has been turned off.
Stay clear of fan blades.
Warning!G
The engine is equipped with a transistorized
ignition system. Because of the high voltage
it is dangerous to touch any components (ig-
nition coils, spark plug sockets, diagnostic
socket) of the ignition system
with the engine running
while starting the engine
if ignition is “on” and the engine is
turned manually
296 Operation
Engine compartment
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.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 37).
The standard display appears in the
multifunction display (
page 127).
Press buttonk orj on the mul-
tifunction steering wheel repeatedly
until the following message appears in
the multifunction display (
page 122):
!Do not use any special lubricant additives,
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.
297 Operation
Engine compartment
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
engine oil” (
page 299).
For more information on engine oil, see
“Fuels, coolants, lubricants, etc.”
(
page 443).Other display messages
If the ignition is not switched on, the fol-
lowing message will appear:
Turn on ignition
to see engine oil level
Switch on the ignition (page 37).
If you see the message:
Observe waiting time
If engine is at operating temperature,
wait 5 minutes before repeating check
procedure.
If engine is not at operating tempera-
ture yet, you must wait 30 minutes
before checking oil.If you see the message:
Cannot check engine
level with engine on
Turn off the engine.
If the engine is at operating tempera-
ture, wait 5 minutes before checking
oil.
If the engine is not at operating
temperature yet, you must wait
30 minutes before checking oil.
iIf you want to interrupt the checking
procedure, press buttonk orj on the
multifunction steering wheel (
page 122).
iIf you want to interrupt the checking
procedure, press buttonk orj on the
multifunction steering wheel (
page 122).
298 Operation
Engine compartment
If there is excess engine oil with the engine
at normal operating temperature, the
following message will appear:
Engine oil level
Reduce oil level
Have excess oil siphoned or drained
off. Contact an authorized
Mercedes-Benz Center.
For more information on messages in the
display concerning engine oil, see the
“Practical hints” section (
page 356).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
stationary 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 294).
Pull out oil dipstick1.
Wipe oil dipstick1 clean.
Fully insert oil dipstick1 into the
dipstick guide tube.
!Excess oil must be siphoned or drained off.
It could cause damage to the engine and
catalytic converter not covered by the
Mercedes-Benz Limited Warranty.
299 Operation
Engine compartment
Pull out oil dipstick1 again after
approximately 3 seconds to obtain
accurate 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
engine oil” (
page 299).
For more information on engine oil, see
“Fuels, coolants, lubricants, etc.”
(
page 443).
For more information on messages in the
multifunction display concerning engine
oil, see the “Practical hints” section
(
page 356).Adding engine oil
Only use approved engine oils and oil fil-
ters required for vehicles with
Maintenance System. For a listing of
approved engine oils and oil filters, refer to
the Factory Approved Service Products
pamphlet (USA only) in your vehicle litera-
ture portfolio, or contact an authorized
Mercedes-Benz Center.
Using engine oils and oil filters of
specification other than those expressly
required for the Maintenance System, or
changing of oil and oil filter at change inter-
vals longer than those called for by the
Maintenance System will result in engine
or emission control system damage not
covered by the Mercedes-Benz Limited
Warranty.
SLK 350 (example illustration)
1Filler cap
SLK 55 AMG
1Filler cap
iThe filling quantity between the upper and
lower marks on the oil dipstick is approximately
2.1 US qt. (2.0 l).
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 443) and
(
page 445).
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.
!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.
306 Operation
Tires and wheels
Tread depth
Do not allow your tires to wear down too
far. Adhesion properties on wet roads are
sharply reduced at tread depths of less
than
1/8in (3 mm).
Treadwear indicators (TWI) are required by
law. These indicators are located in six
places on the tread circumference and
become visible at a tread depth of approx-
imately
1/16in (1.6 mm), at which point the
tire is considered worn and should be re-
placed.
Recommended minimum tire tread depth:
Summer tires 1/8in (3 mm)
Winter tires 1/6in (4 mm)
1TWI (T
read Wear Indicator)
The treadwear indicator appears as a solid
band across the tread.Storing tires
Cleaning tiresWarning!G
Although the applicable federal motor safety
laws consider a tire to be worn when the
treadwear indicators (TWI) become visible at
approximately
1/16in (1.6 mm), we recom-
mend that you do not allow your tires
to wear down to that level. As tread depth
approaches 1/8in (3 mm), the adhesion
properties on a wet road are sharply
reduced.
Depending upon the weather and/or road
surface (conditions), the tire traction varies
widely.!Keep unmounted tires in a cool, dry place
with as little exposure to light as possible.
Protect tires from contact with oil, grease and
gasoline.
!Never use a round nozzle to power wash
tires. The intense jet of water can result in
damage to the tire.
Always replace a damaged tire.
328 Operation
Tires and wheels
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 1 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 (Department of Transportation)
A tire branding symbol which denotes the
tire meets requirements of the
U.S. Department of Transportation.
GAWR (G
ross Axle Weight Rating)
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 Vehicle Weight)
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.GVWR (G
ross Vehicle Weight Rating)
This is the maximum permissible vehicle
weight of the fully loaded vehicle (weight of
the vehicle including all options, passen-
gers, fuel, and cargo and, if applicable,
trailer tongue load). It is indicated on
certification label located on the driver’s
door B-pillar.
Kilopascal (kPa)
The metric unit for air pressure. There are
6.9 kPa to 1 psi; another metric unit for air
pressure is bars. There are 100 kilopascals
(kPa) to 1 bar.
Maximum load rating
The maximum load in kilograms and
pounds that can be carried by the tire.
Maximum loaded vehicle weight
The sum of curb weight, accessory weight,
total load limit and production options
weight.