R129 500SL bj.94 Thermostat change

Merry Christmas to all SL friends !!! Thermostat: What do you say about it? Where does it sit ? And how does it change? Does someone have a photo? And if you are already there you could also change the coolant – how do you do it and what do you take for liquid in what mixing ratio? How warm does your SL get and how is it actually with the big fan – when does it always run? Many greetings