When I bought my car the previous owner had put in non MB coolant. This tends to clog the radiator. Driving in th West Virginia mountains on a 90 degree day the temp would rise to close to 110 and not drop below 100. After having the radiator flushed it was more like 105. After water wetter it would rise but cool to normal in less than a quarter of a mile downhill.
It works but I have this fear of clogging up my radiator even further.
1991 350 SDL