You can mix and match whatever, half & half, none & some, and still it's probably not the problem.
Green, Pink, Yellow......
Green is ok, my 4.5, 30year old aluminum shines nicely with the green glow, but it runs 10 over all the time, I have replaced everything short of the water pump, and I wont let um take it off even for inspection, its a virgin with 117,000 miles, still looks like NEW!
Over the years I have seen some MBZ come into the shop with bad water pumps and go home with one running warm.
They don't overheat, just run warm. So after over 27 years of this we throw up our hands and say oh well.
I have read a lot of threads here about it........still unsolved mystery.
I had to put a water pump on my 300ce, M104 motor, last week, and NEW is all you can get for this motor.
Lucky for me it's running cool as always, with green stuff.
Sorry your coupe is running warm, hope it's something simple.
Sandals (size 11)