
87 Climate control
Te ch n i c a l
data Instruments 
and controlsOperationDrivingInstrument 
cluster displayPractical hints Car care Index 1Temperature selector, left side passenger 
compartment
2Temperature selector, right side passenger 
compartment
3Air volume control switch
4Air distribution control switch
5Rear window defroster
6Economy mode
7Air recirculation, Residual engine heat utilization
8Air volume control for center air outlets, turn wheel 
up to open.
9Air volume control for side air outlet and side 
window defroster outlet, turn wheel up to open.
10Center air outlets, adjustable
11Side air outlet, adjustable
12Windshield air outlet
13Side window defroster outlet, adjustableThe system is always at operational readiness, except 
when manually switched off.
The climate control only operates with the engine 
running.
The temperature selector should be left at the desired 
temperature setting. The temperature selected is 
reached as quickly as possible.
The system will not heat or cool any quicker by setting a 
higher or lower temperature.
The climate control removes considerable moisture from 
the air during operation in the cooling mode. It is 
normal for water to drip on the ground through ducts in 
the underbody. 

91 Climate control
Te ch n i c a l
data Instruments 
and controlsOperationDrivingInstrument 
cluster displayPractical hints Car care Index Air recirculation
This mode can be selected to temporarily reduce the 
entry of annoying odors or dust into the vehicle’s 
interior.
Outside air is not supplied to the vehicle’s interior.
To s el ect ,  p res s O button.
To cancel, press O button again.
The system will automatically switch from recirculated 
air to fresh air
•after approximately 5 minutes at outside 
temperatures below approximately 40°F (5°C),
•after approximately 30 minutes, at outside 
temperatures above approximately 40°F (5°C),
•after approximately 5 minutes, if button S is 
pressed.
At high outside temperatures, the system automatically 
engages the recirculated air mode for approximately 
30 minutes, thereby increasing the cooling capacity 
performance. Press O button again to extend the 
recirculated air mode.Residual engine heat utilization (REST)
With the engine switched off, it is possible to continue 
heating the interior for a short while.
Air volume is controlled automatically. Select 
temperature for each side of the passenger 
compartment. Set air distribution control switch to the 
desired position.
To  s e l e c t :
Turn key in steering lock to position 1 or 0 or remove.
Press O button. Indicator lamp in the button lights 
up.
This function selection will not activate if the battery 
charge level is insufficient.
To  c a n c e l :
Press O button. Indicator lamp in the button goes 
out.
The system will automatically shut off
•if you turn key in steering lock to position 2,
•after approximately 30 minutes,
•if the battery voltage drops. 

187 Malfunction and indicator lamps
Te ch n i c a l
data Instruments 
and controlsOperation DrivingInstrument 
cluster displayPractical hints Car care Index Low engine coolant level warning lamp
With the key in steering lock position 2, the 
warning lamp comes on. It should go out 
when the engine is running.
If the warning lamp does not go out after starting the 
engine, or if it comes on while driving, then the coolant 
level has dropped below the required level. If no leaks 
are noticeable and the engine temperature does not 
increase, continue to drive to the nearest service station 
and have coolant added to the coolant system, see 
page 198.
The low engine coolant level warning light should not be 
ignored. Extended driving with the light illuminated 
may cause serious engine damage not covered by the 
Mercedes-Benz Limited Warranty.
In cases of major or frequent minor coolant loss, have 
the cooling system checked at your authorized 
Mercedes-Benz Center as soon as possible.
Note:
Do not drive without coolant in the cooling system. The 
engine will overheat causing major engine damage.
Monitor the coolant temperature gauge while driving.Low windshield and headlamp washer system fluid 
level warning lamp
With the key in steering lock position 2, the 
warning lamp comes on. It should go out 
when the engine is running.
If the warning lamp does not go out after starting the 
engine, or if it comes on while driving, the level of the 
reservoir has dropped to approximately 1/3 of the total 
volume. The reservoir should be refilled with MB 
Windshield Washer Concentrate “S” and water (or 
commercially available premixed windshield washer 
solvent /antifreeze, depending on ambient temperature - 
see page 199) at the next opportunity. The reservoir for 
the windshield and headlamp washer systems is located 
in the engine compartment.
Wa r n i n g !
Do not spill antifreeze on hot engine parts. 
Antifreeze contains ethylene glycol which may 
burn if it comes into contact with hot engine parts. 
You can be seriously burned. 

198 Coolant level
Te ch n i c a l
data Instruments 
and controlsOperation DrivingInstrument 
cluster displayPractical hintsCar care Index
Coolant level
To check the coolant level, the vehicle must be parked 
on level ground and the engine stopped.
Check coolant level only when coolant is cold.
Adding coolant
If coolant has to be added, a 50/50 mixture of water and 
MB anticorrosion / antifreeze should be added. Refill 
coolant until the float in the reservoir reaches and 
closes the filler opening. Anticorrosion / antifreeze, see page 270. The drain plugs for the cooling system are 
located on the right side of the engine block and at the 
bottom of the radiator.
P20.20-2052-26
Wa r n i n g !
In order to avoid possible serious burns or injury:
• 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 indicates that the engine is 
overheated.• Do not remove pressure cap on coolant 
reservoir if engine temperature is above 194°F 
(90°C). Allow engine to cool down before 
removing cap. The coolant reservoir contains 
hot fluid and is under pressure.• Using a rag, slowly open cap approximately 
1/2 turn to relieve excess pressure. 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. 

266 Fuels, coolants, lubricants etc. - capacities
Te ch n i c a l
data Instruments 
and controlsOperation DrivingInstrument 
cluster displayPractical hints Car care Index
Fuels, coolants, lubricants etc. – capacities
Vehicle components and their respective lubricants must match. Therefore use only brands tested and recommended 
by us. Please refer to the Factory Approved Service Products pamphlet, or inquire at your authorized Mercedes-Benz 
Center.
Model Capacity Fuels, coolants, lubricants etc.
Engine with oil filter SLK 230
SLK 320
SLK 32 AMG6.1 US qt (5.5 l)
8.5 US qt (8.0 l)Recommended engine oils
Automatic transmission 8.5 US qt (8.0 l) Automatic transmission fluid
Manual transmission SLK 230
SLK 3201. 6 U S  q t  ( 1. 5 l )
1. 9 U S  q t  ( 1. 8 l )Transmission oil
Rear axle 1.4 US qt (1.3 l) Hypoid gear oil SAE 90, 85 W 90
Power steering approx. 1.1 US qt (1.0 l) MB Power steering fluid
Front wheel hubs approx. 1.5 oz (43 g) each High temperature roller bearing grease
Brake system approx. 0.5 US qt (0.5 l) MB Brake fluid (DOT 4)
Cooling system SLK 230
SLK 320
SLK 32 AMGapprox. 9.8 US qt (9.3 l)
approx. 11.8 US qt (11.2 l)
approx. 15.3 US qt (14.5 l)MB Anticorrosion / antifreeze 

270 Fuels, coolants, lubricants etc. - capacities
Te ch n i c a l
data Instruments 
and controlsOperation DrivingInstrument 
cluster displayPractical hints Car care Index
Gasoline additives 
A major concern among engine manufacturers is carbon 
build up caused by gasoline. Mercedes-Benz 
recommends the use of only 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 loss.
Do not blend other specific fuel additives with fuel. 
They only result in unnecessary cost, and may be 
harmful to the engine operation.
Damage or malfunctions resulting from poor fuel 
quality or from blending specific fuel additives are not 
covered by the Mercedes-Benz Limited Warranty.Coolants
The engine coolant is a mixture of water and 
anticorrosion / antifreeze, which provides:
•corrosion protection,
•freeze protection,
•boiling protection (by increasing the boiling point).
The cooling system was filled at the factory with a 
coolant providing freeze protection to approximately 
-22°F (-30°C) and corrosion protection.
If the antifreeze mixture is effective to -22°F (-30°C), the 
boiling point of the coolant in the pressurized cooling 
system is reached at approximately 266°F (130°C).
The coolant solution must be used year round to provide 
the necessary corrosion protection and increase in the 
boil-over protection. You should have it replaced every 
3years.
To provide the important corrosion protection, the 
solution must be at least 45% anticorrosion / antifreeze 
(equals a freeze protection to approx. - 22 °F [- 30 °C]). If 
you use a solution that is more than 55% anticorrosion /
antifreeze (freeze protection to approx. - 49 °F [- 45°C]),  

271 Fuels, coolants, lubricants etc. - capacities
Te ch n i c a l
data Instruments 
and controlsOperation DrivingInstrument 
cluster displayPractical hints Car care Index the engine temperature will increase due to the lower 
heat transfer capability of the solution. Therefore, do not 
use more than this amount of anticorrosion / antifreeze.
If the coolant level is low, water and MB anticorrosion /
antifreeze should be used to bring it up to the proper 
level (have cooling system checked for signs of leakage).
The water in the cooling system must meet minimum 
requirements, which are usually satisfied by normal 
drinking water. If your are not sure about the water 
quality, consult your authorized Mercedes-Benz Center.
Anticorrosion / antifreeze
Your vehicle contains a number of aluminum parts. The 
use of aluminum components in motor vehicle engines 
necessitates that anticorrosion / antifreeze coolant used 
in such engines be specifically formulated to protect the 
aluminum parts. (Failure to use such anticorrosion /
antifreeze coolant will result in a significantly 
shortened service life.)
Therefore the following product is strongly 
recommended for use in your vehicle: Mercedes-Benz 
Anticorrosion / Antifreeze Agent.Before the start of the winter season (or once a year in 
the hot southern regions), you should have the 
anticorrosion / antifreeze concentration checked. The 
coolant is also regularly checked each time you bring 
your vehicle to your authorized Mercedes-Benz Center 
for service.
Anticorrosion / antifreeze quantity
Model Approx. freeze protection
– 35°F
(– 37°C)– 49°F
(– 45°C)
SLK 230 KOMPRESSOR 4.9 US qt
(4.7 l)5.4 US qt
(5.1 l)
SLK 320 5.9 US qt
(5.6 l)6.5 US qt
(6.1 l)
SLK 32 AMG 7.7 US qt
(7.3 l)8.5 US qt
(8.0 l)