Any time you check the oil level thru the instrument cluster(2000 & later) the car HAS to be driven & then in a checked when the car is LEVEL.
Adding oil is fine but remember to drive for a while before checking. On the W203 chassis there isn't any dipstick & the special factory tool costs around $150.
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)