Guys,
my car was running fine until few days ago. 80-82 degrees during city driving.
Now it was almost touching 100+

I added coolant and washer fluid bought from autozone.

Do you guys think this is the problem?
If so what coolant should i use.

Can i just add MB coolant or should i flush old one out and add MB one??

Really need help with this. Thanks in advance.

Note: Radiator was replaced in Jan-08 and found no oil or water leaks underneath car.

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1) '04 S500 Gold/Beige......120k Miles
2) '93 300E 2.8...Green/Tan MBTex..........202k Miles(and going)
3) '89 420SEL...Light Blue/gray Leather....155k Miles (Retired )