Removing thermostat is common practice here in India, especially in European origin diesels, the Japanese diesels never run anything over 80c and if they do, it is trouble with capital T.

Most OM 616 used in commercial LCV app would not only remove the thermostat, they would remove the radiator cap as well, according to them, it is the only effective way to keep it cool when loaded with 5 tons of goods.

My OM 616 turbo never goes a shade over 85c and that in a 45c outside weather day. I just wont feel comfortable at 100c as I know how high the hot spots inside the engine are by then, also it is like a psychological barrier once you cross 100c, overheating is on its' way. The turbo OM 616 is equipped with a 72c thermostat and I saw a big drop in temps when I modified the air intake to a ram air system as well a removed the muffler.

It is different approach I guess, I drive my brother's Toyota diesel SUV which never goes over 80c, fully loaded with a/c on at around 45c and yet, any MB diesel at that situation is showing the dreaded temp creep.

I have used Watter Wetter when I used to live in NY with my 240D as well as Accord V6, did not see any adverse reaction except for gelling inside the radiator which made me a bit nervous.