C240 Coolant/Anti-Freeze Flushing

[EPineda]

Help! I just bought a used 2003 C240 4Matic with over 50,000 miles. While checking the fluids, I noticed bluish/greenish color on the coolant/anti-freeze reservoir as if the original CLEAR-colored MB coolant has been inter-mized with non-MB fluid. I would like to drain the coolant completely and replaced with original MB but unsure where to look for the radiator and engine coolant drain plugs and how many are in this car, as well as the engine air purge(?) plug if any. I done this before on my 300E and it was quite easy. I am just not familiar with this model.

Can anyone please help me by telling me where to look or to find the drain plugs and how many coolant drains I need to open for a complete flush? Is it also recommended to replace the thermostat?

Thanks an awful lot!