Finally found a lower temp. thermostat!
Quite by accident, I discovered a lower temperature thermostat for my '84 500sel while I was parting out an '81 380sel. It had a 75 C Behr thermostat( # 002 203 77 75). I put it in a pot of hot water along with a brand new 84 C degree one from the Mercedes dealer, and guess what? The 84 degree one was closed tight at 190 degrees FAhrenheit and the 75 C one was WIDE OPEN!! I live in Phoenix where it gets up to 100 by May and 110-115 July and August. I am hoping this will lower my engine temperature by 10 degrees in the summer. What do you guys think?