Mercedes-Benz 2005 M-Class Operator's Manual page 226

Operation
Engine compartment
Checking engine oil level via display
When checking the oil level the vehicle
must
be parked on level ground
be at normal operating temperature
have been stationary for at least five
minutes with the engine turned off
To check the engine oil level via the display
in the speedometer, do the following:
Turn the key in the steering lock to
position 2.
1 Button
2 Display in speedometer
224
Wait until the display
------
the speedometer display 2.
Within one second press button 1
twice.
One of the following messages will
subsequently appear in the display:
OIL i.O
The oil level is correct. Engine oil
does not to be added.
– 1.0 L
Add 1.0 liter of engine oil.
– 1.5 L
Add 1.5 liters of engine oil.
– 2.0 L
Add 2.0 liters of engine oil.
For adding engine oil see ( page 314).
For more information on engine oil, see the
"Technical data" section ( page 312) and
( page 314).
appears in Other display messages
If there is excess engine oil with the engine
at normal operating temperature, the
following message will appear in the
display:
OIL HI
The oil level is too high.
Have excess oil siphoned.
!
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.