2012 MERCEDES-BENZ SLK-CLASS ROADSTER coolant temperature

Display messagesPossible causes/consequences and M Solutions?The engine fan is defective.XAt coolant temperatures under 248 ‡(120 †), drive to the next
qualified specialist workshop.XAvoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and stop-and-go traffic.?
Coolant Stop car,
switch engine offThe coolant is too hot.XPull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.XMake sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.XWait until the display message disappears before restarting the
engine. Otherwise, the engine could be damaged.XPay attention to the coolant temperature display.XIf the temperature increases again, visit a qualified specialist
workshop immediately.GWARNING
Driving when your engine is overheated can cause some fluids which may have leaked into the
engine compartment to catch fire. You could be seriously burned.
Steam from an overheated engine can cause serious burns which can occur just by opening the
engine hood. Stay away from the engine if you see or hear steam coming from it.
Stop the vehicle in a safe location away from other traffic. Turn off the engine, get out of the
vehicle and do not stand near the vehicle until the engine has cooled down.
! If the coolant temperature is over 248 ‡ (120 †), do not continue driving. The engine will
otherwise be damaged.
Display messages217On-board computer and displaysZ

ProblemPossible causes/consequences and M Solutions?
The red coolant
warning lamp lights up
while the engine is
running and the coolant
temperature gauge is
at the start of the scale.The temperature sensor for the coolant temperature gauge is
defective.
The coolant temperature is no longer being monitored. There is a
risk of engine damage if the coolant temperature is too high.XPull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions. Do not continue
driving under any circumstances.XApply the electric parking brake.XConsult a qualified specialist workshop.Warning and indicator lamps in the instrument cluster235On-board computer and displaysZ

ProblemPossible causes/consequences and M Solutions?
The red coolant
warning lamp comes on
while the engine is
running.The coolant level is too low.
If the coolant level is correct, the airflow to the engine radiator
may be blocked or the electric engine radiator fan may be
malfunctioning.
The coolant is too hot and the engine is no longer being cooled
sufficiently.XObserve the additional display messages in the multifunction
display.XPull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.XAllow the engine and coolant to cool.XCheck the coolant level and add coolant (Y page 262). Observe
the warning notes.XIf you need to add coolant more often than usual, have the
engine coolant system checked.XMake sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.XAt coolant temperatures under 248 ‡(120 †), drive to the next
qualified specialist workshop.XAvoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and start/stop traffic.?
The red coolant
warning lamp comes on
while the engine is
running. A warning tone
also sounds.The coolant temperature has exceeded 248 ‡ (120 †). The
airflow to the engine radiator may be blocked or the coolant level
may be too low.
The engine is not being cooled sufficiently and may be damaged.XObserve the additional display messages in the multifunction
display.XPull over and stop the vehicle safely and switch off the engine,
paying attention to road and traffic conditions.XAllow the engine and coolant to cool.XCheck the coolant level and add coolant (Y page 262). Observe
the warning notes.XIf you need to add coolant more often than usual, have the
engine coolant system checked.XMake sure that the air supply to the engine radiator is not
blocked, e.g. by snow, slush or ice.XAt coolant temperatures under 248 ‡(120 †), drive to the next
qualified specialist workshop.XAvoid subjecting the engine to heavy loads, e.g. driving in
mountainous terrain, and start/stop traffic.236Warning and indicator lamps in the instrument clusterOn-board computer and displays

GWARNING
Driving when your engine is overheated can cause some fluids which may have leaked into the
engine compartment to catch fire. You could be seriously burned.
Steam from an overheated engine can cause serious burns which can occur just by opening the
engine hood. Stay away from the engine if you see or hear steam coming from it.
Stop the vehicle in a safe location away from other traffic. Turn off the engine, get out of the
vehicle and do not stand near the vehicle until the engine has cooled down.
! If the coolant temperature is over 248 ‡ (120 †), do not continue driving. The engine will
otherwise be damaged.
Driving systems
ProblemPossible causes/consequences and M Solutions·
The red distance
warning lamp lights up
while the vehicle is in
motion. A warning tone
also sounds.GRisk of accident
You are approaching a vehicle or a stationary obstacle in your line
of travel at too high a speed.
XBe prepared to brake immediately.XPay careful attention to the traffic situation. You may have to
brake or take evasive action.
More information about DISTRONIC PLUS ( Y page 158) and
PRE-SAFE ®
Brake ( Y page 62).
Warning and indicator lamps in the instrument cluster237On-board computer and displaysZ

Adding engine oilGWARNING
If engine oil comes into contact with hot
engine parts, it may ignite and you could burn
yourself. Do not spill any engine oil on hot
engine parts.
HEnvironmental note
When adding oil, take care not to spill any. If
oil enters the soil or waterways, it is harmful
to the environment.
! Only use engine oils and oil filters that
have been approved for vehicles with a
service system. You can obtain a list of the
engine oils and oil filters tested and
approved in accordance with the
Mercedes-Benz Specifications for Service
Products at any Mercedes-Benz Service
center.
Damage to the engine or exhaust system is
caused by the following:
R using engine oils and oil filters that have
not been specifically approved for the
service system
R replacing engine oil and oil filters after
the interval for replacement specified by
the service system has been exceeded
R using engine oil additives.
! Do not add too much oil. adding too much
engine oil can result in damage to the
engine or to the catalytic converter. Have
excess engine oil siphoned off.
Example: engine oil cap
XTurn cap : counterclockwise and remove
it.XAdd engine oil.
If the oil level is at or below the MIN mark
on the oil dipstick, add 0.55 US qt to
1.1 US qt (0.5 to 1.0 l) of engine oil.XReplace cap : on the filler neck and turn
clockwise.
Ensure that the cap locks into place
securely.XCheck the oil level again with the oil
dipstick ( Y page 261).
Further information on engine oil
( Y page 326).
Checking and adding other service
products
Checking the coolant level
GWARNING
In order to avoid any potentially serious burns:
R 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 display indicates
that the coolant is overheated.
R do not remove the pressure cap on the
coolant reservoir if the coolant temperature
is above 158 ‡ (70 †). Allow the engine to
cool down before removing the cap. The
coolant reservoir contains hot fluid and is
under pressure.
262Engine compartmentMaintenance and care

Rusing a rag, slowly turn the cap
approximately 1
/ 2 turn to relieve excess
pressure. If opened immediately, scalding
hot fluid and steam will be blown out under
pressure.
R do not spill antifreeze on hot engine parts.
Antifreeze contains ethylene glycol which
may burn if it comes into contact with hot
engine parts.XPark the vehicle on a level surface.
Only check the coolant level when the
vehicle is on a level surface and the engine
has cooled down.XTurn the SmartKey to position 2 in the
ignition lock ( Y page 131).
On vehicles with KEYLESS-GO, press the
Start/Stop button twice ( Y page 131).XCheck the coolant temperature display in
the instrument cluster.
The coolant temperature must be below
158 ‡ (70 †).XTurn the SmartKey to position
0 (Y page 131) in the ignition lock.XSlowly turn cap ; half a turn counter-
clockwise to allow excess pressure to
escape.XTurn cap ; further counter-clockwise and
remove it.
If the coolant is at the level of marker bar
= in the filler neck when cold, there is
enough coolant in coolant expansion
tank :.
If the coolant level is approximately 0.6 in
(1.5 cm) above marker bar = in the fillerneck when warm, there is enough coolant
in coolant expansion tank :.XIf necessary, add coolant that has been
tested and approved by Mercedes-Benz.XReplace cap ; and turn it clockwise as far
as it will go.
For further information on coolant, see
( Y page 327).
Adding washer fluid to the windshield
washer system/headlamp cleaning
system
GWARNING
Washer solvent/antifreeze is highly
flammable. Do not spill washer solvent/
antifreeze on hot engine parts, because it may
ignite and burn. You could be seriously
burned.
XTo open: pull cap : upwards by the tab.XAdd the premixed washer fluid.XTo close: press cap : onto the filler neck
until it engages.
The washer fluid reservoir is used for both the
windshield washer system and the headlamp
cleaning system.
Further information on windshield washer
fluid/antifreeze ( Y page 328).
Brake fluid level
! If the brake fluid level in the brake fluid
reservoir has fallen to the MIN mark or
below, check the brake system
Engine compartment263Maintenance and careZ

Filling capacities
The following values refer to an oil change
including the oil filter.
ModelCapacitySLK 2505.8 US qt (5.5 l)SLK 3506.9 US qt (6.5 l)SLK 55 AMG10.0 US qt (9.5 l) 24
Additives
!
Do not use any additives in the engine oil.
This could damage the engine.
Engine oil viscosity
Viscosity describes the flow characteristics
of a fluid. If an engine oil has a high viscosity,
this means that it is thick; a low viscosity
means that it is thin.
Select an engine oil with an SAE (viscosity)
classification suitable for the prevailing
outside temperatures. The table shows you
which SAE classifications are to be used. The
low-temperature characteristics of engine
oils can deteriorate significantly, e.g. as a
result of aging, soot and fuel deposits. It is
therefore strongly recommended that you
carry out regular oil changes using an
approved engine oil with the appropriate SAE
classification.
Brake fluidGWARNING
Over a period of time, the brake fluid absorbs
moisture from the air; this lowers its boiling
point.
If the boiling point of the brake fluid is too low,
vapor pockets may form in the brake system
when the brakes are applied hard (e.g. when
driving downhill). This would impair braking
efficiency.
You should have the brake fluid renewed at
regular intervals. The brake fluid change
intervals can be found in the Maintenance
Booklet.
Only use brake fluid approved by Mercedes-
Benz. Information about approved brake fluid
can be obtained at any qualified specialist
workshop or on the Internet at
http://bevo.mercedes-benz.com.
Coolant
Important safety notes
GWARNING
Antifreeze is highly flammable. Fire, naked
flames and smoking are prohibited when
handling antifreeze.
If antifreeze comes into contact with hot
engine parts, it may ignite and you could burn
yourself. Do not spill any antifreeze on hot
engine parts.
! Only add coolant that has been premixed
with the desired antifreeze protection. You
could otherwise damage the engine.
Further information on coolants can be
found in the Mercedes-Benz Specifications
for Service Products, MB Specifications for
Service Products 310.1, e.g. on the
Internet at
http://bevo.mercedes-benz.com. Or
contact a qualified specialist workshop.
24 Including external oil cooler.Service products and filling capacities327Technical dataZ

! Always use a suitable coolant mixture,
even in countries where high temperatures
prevail.
Otherwise, the engine cooling system is not
sufficiently protected from corrosion and
overheating.
The coolant is a mixture of water and
antifreeze/corrosion inhibitor. It performs
the following tasks:
R corrosion protection
R antifreeze protection
R raising the boiling point
If the coolant has antifreeze protection down
to -35 ‡ (-37 †), the boiling point of the
coolant under operating conditions is
approximately 266 ‡ (130 †).
The antifreeze/corrosion inhibitor
concentration in the engine cooling system
should:
R be at least 50 %. This will protect the engine
cooling system against freezing down to
approximately -35 ‡ (-37 †).
R not exceed 55% (antifreeze protection
down to -49 ‡ [-45 †]). Otherwise, heat
will not be dissipated as effectively.
If the vehicle has lost coolant, add equal
amounts of water and antifreeze/corrosion
inhibitor. Mercedes-Benz recommends an
antifreeze/corrosion inhibitor concentrate in
accordance with MB Specifications for
Service Products 310.1.
The coolant is checked with every
maintenance interval at a qualified specialist
workshop.
i When the vehicle is first delivered, it is
filled with a coolant mixture that ensures
adequate antifreeze and corrosion
protection.CapacityModelCapacitySLK 250Approx. 10.1 US qt (9.6 l)SLK 350Approx. 11.0 US qt(10.4 l)SLK 55 AMGApprox. 10.0 US qt (9.5 l)
iUse MB 325.0 or MB 326.0 corrosion
inhibitor/antifreeze.
Washer fluid
GWARNING
Washer solvent/antifreeze is highly
flammable. Do not spill washer solvent/
antifreeze on hot engine parts, because it may
ignite and burn. You could be seriously
burned.
! Only use washer fluid that is suitable for
plastic lamp lenses, e.g. MB SummerFit or
MB WinterFit. Unsuitable washer fluid
could damage the plastic lenses of the
headlamps.
! Do not add distilled or de-ionized water to
the washer fluid container. Otherwise, the
level sensor may be damaged.
! Only MB SummerFit and MB WinterFit
washer fluid should be mixed together. The
spray nozzles may otherwise become
blocked.
At temperatures above freezing:
XFill the washer fluid reservoir with a mixture
of water and windshield washer fluid, e.g.
MB SummerFit.XAdd 1 part MB SummerFit to 100 parts
water.328Service products and filling capacitiesTechnical data