Think of this: 100 degrees centigrade is boiling point of water or 212 degrees F. Zero degrees C. is water freeze point or 32 degrees F. The difference between the two is 180 degrees F. Therefore 50 degrees C equals (90 + 32)
122 degrees F.

O d.C = 32 d.F
50 d.C = 122 d.F
100 d.C = 212 d.F


That will give you some reference. And no -- 100 d. C. is not too hot.....many engines are designed to run much higher than boiling (212 d.F) in order to maintain engine tuning for emissions purposes. With a 50/50 mix of antifreeze/water and a good radiator pressure cap, you car will not "boil" until much higher.....oh, say, 240 degrees F.

Regards

Run-em
1983 300SD - aka - SPARKY THE DIESEL