Page 345 of 561

344 OperationAt the gas stationCoolant
For normal replenishing, use water (pota-
ble water quality). For more information,
see “Coolant level” (
page 351) and
“Fuels, coolants, lubricants, etc.”
(
page 521).
Brake fluidWindshield / rear window washer
system and headlamp cleaning
system*
For more information on refilling the reser-
voir, see “Windshield / rear window washer
system and headlamp cleaning system*”
(
page 352).
Vehicle lighting
Check function and cleanliness. For infor-
mation on replacing light bulbs, see “Re-
placing bulbs” (
page 465).
For more information, see “Exterior lamp
switch” (
page 147).
Tire inflation pressure
For more information, see “Checking tire
inflation pressure” (
page 365).
!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 Light
Truck Center immediately. Do not add
brake fluid as this will not solve the
problem. For more information, see
“Brake fluid” (
page 523).
Page 346 of 561

345 Operation
Engine compartment
Engine compartment
Hood
Opening
1Hood lock release lever
Pull release lever1 downwards.
The hood is unlocked. Handle2 pro-
trudes slightly from the radiator grille.
If not, lift the hood slightly.
2Handle for opening the hood
Press and hold handle2 in direction
of arrow.
The hood is unlocked.
Pull up on the hood and then release it.
The hood will be automatically held
open at shoulder height by gas-filled
struts.
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.
!To avoid damage to the windshield wip-
ers or hood, never open the hood if the
wiper arms are folded forward away
from the windshield.
Warning!
G
To help prevent personal injury, stay clear of
moving parts when the hood is open and the
engine is running. Make sure the hood is
properly closed before driving. When closing
the hood, use extreme caution not to catch
hands or fingers.
The radiator fan may continue to run for ap-
proximately 30 seconds or even restart af-
ter the engine has been turned off. Stay
clear of fan blades.
Page 347 of 561

346 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. Increased 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 gauge 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. 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 (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
Warning!
G
Be careful that you do not close the hood on
anyone.!Do not push the hood closed manually,
as this could damage it.
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 Mercedes-Benz Light
Truck Center.
Page 348 of 561

347 Operation
Engine compartment
Checking engine oil level with the
control system (R 500 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 yet, 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 38).
The standard display (
page 168) should
appear in the multifunction display.
Press buttonk orj on the
steering wheel until the following
message appears in the multifunction
display:
One of the following messages will
subsequently appear in the indicator:
Engine oil level ok
Add 1.0 qt. to reach max. oil
level(Canada:
1.0 liter
)
Add 1.5 qts. to reach max. oil
level(Canada:
1.5 liters
)
Add 2.0 qts. to reach max. oil
level(Canada:
2.0 liters
)
If necessary, add engine oil.
For adding engine oil, see (
page 523).
For more information on engine oil, see the
“Technical data” section (
page 521) and
(
page 523).
Other display messages
If the SmartKey is not turned to position2
in the starter switch, the following
message will appear:
Switch ignition on
to check engine oil level
Switch on the ignition (
page 38).
iIf you want to interrupt the checking
procedure, press thek orj
button on the multifunction steering
wheel.
Page 349 of 561

348 OperationEngine compartmentIf you see the message:Observe waiting period
If engine is at operating temperature,
wait 5 minutes before repeating check
procedure.
If engine is not at operating tempera-
ture, wait 30 minutes before repeating
check procedure.
If you see the message:
Engine oil level
Not when 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 temper-
ature yet, you must wait 30 minutes
before checking oil.If there is excess engine oil with the engine
at 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 Light Truck Center.
For more information on messages in the
display concerning engine oil, see the
“Practical hints” section (
page 437).Checking engine oil level with the oil
dipstick (R 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 yet, the vehicle also must
have been stationary for at least
5 minutes with the engine turned off
!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.
Page 350 of 561

349 Operation
Engine compartment
To check the engine oil level with the oil
dipstick, do the following:
Open the hood (
page 345).
1Oil dipstick
2Upper mark
3Lower mark
Pull out oil dipstick1.
Wipe oil dipstick 1 clean.
Fully insert oil dipstick1 into the
dipstick guide tube.
Pull out oil dipstick1 again after
approximately 3 seconds to obtain
accurate reading.The oil level is correct when it is between
lower mark 3 (min.) and upper mark 2
(max.) mark of the oil dipstick.
If necessary, add engine oil.
For more information on engine oil, see
“Technical data” section (
page 521) and
(
page 523).
See the “Practical hints” section
(page 437) if the low engine oil level
warning lamp in the instrument cluster
flashes.Adding engine oiliThe filling quantity between the upper
and lower marks on the oil dipstick is
approximately 2.1 US qt. (2.0 l).
!Only use approved engine oils and oil
filters required for vehicles with Main-
tenance System (U.S. vehicles) or
FSS PLUS (Canada vehicles). For a list-
ing of approved engine oils and oil fil-
ters, refer to the Factory Approved
Service Products pamphlet in your ve-
hicle literature portfolio, or contact an
authorized Mercedes-Benz Light Truck
Center.
Using engine oils and oil filters of spec-
ification other than those expressly re-
quired for the Maintenance System
(U.S. vehicles) or FSS PLUS (Canada
vehicles), or changing of oil and oil filter
at change intervals longer than those
called for by the Maintenance System
(U.S. vehicles) or FSS PLUS (Canada
vehicles) will result in engine damage
not covered by the Mercedes-Benz
Limited Warranty.
Page 351 of 561
350 OperationEngine compartmentR3501Filler capR5001Filler cap
Unscrew filler cap1 from filler neck.
Add engine oil as required. Never over-
fill 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” section (
page 521) and
(
page 523).
Transmission fluid level
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 Light
Truck Center check the automatic trans-
mission.
!Excess oil must be siphoned or drained
off. It will cause damage to the engine
and catalytic converter not covered by
the Mercedes-Benz Limited Warranty.
Page 352 of 561

351 Operation
Engine compartment
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.
1Cap
2Coolant expansion tank
3Indicator wall
4Coolant level
Using a rag, turn cap 1 slowly approx-
imately one half turn counterclockwise
to release any excess pressure.
Continue turning cap 1 counterclock-
wise and remove it.
Coolant level 4 is correct if the level:
for cold coolant: reaches the top of
indicator wall 3 visible through the
filling opening
for warm coolant: is approximately
0.6 in (1.5 cm) higher
Add coolant as required.
Replace and tighten cap 1.
For more information on coolant, see the
“Technical data” section (
page 525).
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
1/2 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 gly-
col which may burn if it comes into con-
tact with hot engine parts.