I recently went thru 2 separate Stant thermostats on a rover with the in-line mod. The first was nearly new and stuck wide open. The second resulted in my temps fluctuating constantly between 174 and 196 up and down like a yo-yo. And it was a 180 not a 190. I thought maybe it was an air pocket and worked that angle for a while. Finally replaced with a Motorad and she now stays from 181 to 188.

The moral of this story is stay away from Stant products.

 

I use warm weather thermostat from Atlantic British now for a total of 7 years no issues