Which thermostat?

[Bruce Parker (RIP)]

I've run with and without. In warm weather I can't tell the difference (I don't run it in the cold very often). Right now I have a pair of 165 degree ones, just because, as you say, they were there for a reason. One thing I always do is cook new thermostats on the stove to make sure they open before I install them. Some new old stock ones don't open.

[Lynn Eades]

Mike, I'd only buy wax ones.

[Andrew Rowe]

Is there not a technical reason for running thermostats?, that seems to be lost on a lot of people. I always understood, the reason for using them was that the engine was brought up to correct optimum operating temperature quickly , and maintained at this even temperature for the running efficiency of the engine. It also slows the circulation of the water to allow heat to dissipate through the radiator core, rather than circulating too fast......just my thoughts, Cheers Andrew.

[Lynn Eades]

Pretty much on the nail Andrew. They (stats) don't keep the temp down, they keep it up, and even,...... if everything else is in good order, (as you already know)