my m103 used to run around 80C constantly, but due to a crack in my original coolant tank, I was forced to replace it today and did an entire drain/refill of the system along with a new 87C thermostat
now it seems to run at 87C only when I am driving 70mph on the freeway night or day. When I am cruising in the city, it starts creeping around 95C to 100C.