2003 MERCEDES-BENZ CLK320 CABRIOLET Owner's Manual

318 Fuels, coolants, lubricants etc.
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Engine oils
Engine oils are specifically tested for their suitability in
our engines. Therefore, use only engine oils
recommended by Mercedes-Benz. Information on
recommended brands is available in the Factory
Approved Service Products pamphlet or at your
authorized Mercedes-Benz Center.
Please follow Service Booklet recommendations for
scheduled oil changes. Failure to do so could result in
engine damage not covered by the Mercedes-Benz
Limited Warranty.
Engine oil additives
Do not blend oil additives with engine oil. They may be
harmful to the engine operation.
Damage or malfunctions resulting from blending oil
additives are not covered by the Mercedes-Benz Limited
Warranty.Air conditioner refrigerant
R-134a (HFC) refrigerant and special PAG lubricating oil
is used in the air conditioner system.
Never use R-12 (CFC) or mineral-based lubricating oil,
otherwise damage to the system will occur.
Brake fluid
During vehicle operation, the boiling point of the brake
fluid is continuously reduced through the absorption of
moisture from the atmosphere. Under extremely hard
operating conditions, this moisture content can lead to
the formation of bubbles in the system thus reducing
the system’s efficiency.
The brake fluid must therefore be replaced every two
years, preferably in the spring.
It is recommended to use only brake fluid approved by
Mercedes-Benz. Your authorized Mercedes-Benz Center
will provide you with additional information.

319 Fuels, coolants, lubricants etc.
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Caution!
To maintain the engine’s durability and performance,
premium unleaded gasoline must be used. If premium
unleaded is not available and low octane fuel is used,
follow these precautions:
•Have the fuel tank filled only partially with
unleaded regular and fill up with premium
unleaded as soon as possible.
•Avoid full throttle driving and abrupt acceleration.
•Do not exceed an engine speed of 3000 rpm, if the
vehicle is loaded with a light load such as two
persons and no luggage.
•Do not exceed 2/3 of maximum accelerator pedal
position, if the vehicle is fully loaded or operating in
mountainous terrain.Fuel requirements
Use only Premium unleaded meeting ASTM
standard D 439:
The octane number (posted at the pump) must be
91 min. It is an average of both the Research (R) octane
number and the Motor (M) octane number: [(R+M)/2].
This is also known as 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..

320 Fuels, coolants, lubricants etc.
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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 boil-
over protection. You should have it replaced every 15
years or 150 000 miles (250 000 km), whichever comes
first. Coolant system design and coolant used stipulate
the replacement interval. The above replacement
interval is only applicable if MB 325.0 anticorrosion/
antifreeze solution or other Mercedes-Benz approved
products of equal specification (see Factory Approved
Service Products pamphlet) are used to renew the
coolant concentration or bring it back up to the proper
level.

321 Fuels, coolants, lubricants etc.
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cluster displayPractical hints Car care Index 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]),
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 325.0
anticorrosion/ antifreeze should be used to bring it up
to the proper level (have cooling system checked for
signs of leakage).
Please make sure that the mixture is in accordance with
label instructions.
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
325.0 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)
CLK 320 4.8 US qt
(4.5 l)5.3 US qt
(5.0 l)
CLK 430 5.9 US qt 6.5 US qt

322 Consumer information
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Consumer information
This has been prepared as required of all manufactures
of passenger cars under Title 49, Code of U.S. Federal
Regulations, Part 575 pursuant to the “National Traffic
and Motor Vehicle Safety Act of 1966”.
Uniform tire quality grading
Quality grades can be found where applicable on the
tire sidewall between tread shoulder and maximum
section width. For example:
All passenger vehicle tires must conform to federal
safety requirements in addition to these grades.
Treadwear
The treadwear grade is a comparative rating based on
the wear rate of the tire when tested under controlled
conditions on a specified government test course. For
example, a tire graded 150 would wear one and one-half
(1
1/2) times as well on the government course as a tire
graded 100. The relative performance of tires depends
upon the actual conditions of their use, however, and may depart significantly from the norm due to
variations in driving habits, service practices and
differences in road characteristics and climate.
Traction
The traction grades, from highest to lowest are AA, A, B,
and C. Those grades represent the tire’s ability to stop
on wet pavement as measured under controlled
conditions on specified government test surfaces of
asphalt and concrete. A tire marked C may have poor
traction performance.
Tread wear 200 Traction AA Temperature A
Wa r n i n g !
The traction grade assigned to this tire is based on
straightahead braking traction tests, and does not
include acceleration, cornering, hydroplaning, or
peak traction characteristics.

323 Consumer information
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The temperature grades are A (the highest), B, and C,
representing the tire’s resistance to the generation of
heat and its ability to dissipate heat when tested under
controlled conditions on a specified indoor laboratory
test wheel. Sustained high temperature can cause the
material of the tire to degenerate and reduce tire life,
and excessive temperature can lead to sudden tire
failure. The grade C corresponds to a level of
performance which all passenger vehicle tires must
meet under the Federal Motor Vehicle Safety Standard
No. 109. Grades B and A represent higher levels of
performance on the laboratory test wheel than the
minimum required by law.
Wa r n i n g !
The temperature grade for this tire is established
for a tire that is properly inflated and not
overloaded. Excessive speed, underinflation, or
excessive loading, either separately or in
combination, can cause excessive heat build up
and possible tire failure.

324 Index
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Index
AABS (Antilock brake system) ....................................... 214
Malfunction indicator lamp..................................... 227
ABS-SYSTEM - malfunction and
warning messages ......................................................... 233
Adjusting headlamp aim............................................... 282
Adjusting telescoping steering column ........................ 73
Air conditioner refrigerant............................................ 318
Air distribution .............................................................. 120
Air volume ...................................................................... 120
Airbag deactivation system ............................................ 59
Airbag OFF indicator lamp ........................................... 228
Airbags .............................................................................. 61
Alarm system ............................................................. 39, 40
Antenna
Removal ...................................................................... 295
Anticorrosion/antifreeze .................... 208, 254, 316, 321
Antiglare night position.................................................. 74
Antilock brake system (ABS) ....................................... 214
Malfunction indicator lamp..................................... 227
Antitheft alarm system ................................................... 39
Aquaplaning ...................................................................205Armrest, rear bench ....................................................... 152
Ashtray
Center console, front ................................................ 150
Audio system ..................................................................123
Anti-theft system ....................................................... 125
Button and soft key operation ................................. 126
Cassette mode ............................................................ 131
CD changer ................................................................. 136
CD mode ..................................................................... 135
Operating and display elements .............................124
Operating safety ........................................................ 123
Operation ....................................................................127
Operation – audio and telephone ........................... 123
Radio mode ................................................................ 129
Telephone operation ................................................. 139
Audio systems ................................................................... 89
Cassette player ............................................................ 91
CD player ......................................................................90
Radio ............................................................................. 89
Automatic central locking .............................................. 34
Automatic climate control ............................................ 116
Air distribution .......................................................... 120
Air recirculation ........................................................ 121
Air volume.................................................................. 120
Basic setting............................................................... 118
Defogging windows ................................................... 119

325 Index
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cluster displayPractical hints Car careIndex Defrosting .................................................................... 119
Display and controls ..................................................118
Dust filter ................................................................... 122
Economy ...................................................................... 119
Rear window defroster ............................................. 120
Residual engine heat utilization (REST) ............... 121
Special settings .......................................................... 119
Automatic transmission................................................ 191
Emergency operation ............................................... 199
Fluid level................................................................... 253
Program mode selector switch................................ 198
Selector lever position.............................................. 194
Transmission selector lever,
manually unlocking .................................................. 276
BBabySmart
TM airbag deactivation system..................... 59
Self-test ......................................................................... 59
Backrest, front seat.......................................................... 49
BAS (Brake assist system) ............................................ 212
Malfunction indicator lamp..................................... 227
Battery ............................................................................. 270
Battery recycling ....................................................... 271BATTERY/ALTERNATOR - malfunction and warning
messages ................................................................... 232
Block heater ................................................................... 209
BRAKE ASSIST - malfunction and
warning messages ........................................................ 233
Brake assist system (BAS) ............................................. 212
Malfunction indicator lamp .................................... 227
Brake fluid...................................................... 225, 316, 318
Capacity ...................................................................... 316
BRAKE FLUID - malfunction and
warning messages ........................................................ 234
BRAKE LINING WEAR - malfunction and
warning messages ........................................................ 234
Brake pad wear .............................................................. 234
Brake warning lamp ..................................................... 225
Brake fluid low ......................................................... 225
Brakes .................................................... 200, 202, 212, 216
Bulbs
See Replacing bulbs................................................. 277