Technical Thermostat sealant of choice

Like you, I have never had any leak, and I have always used a gasket cement on the gasket.
Can’t believe the problems that most on here have had.

 

Your bolts aren't bottoming out in the manifold??
I also surfaced both faces (as others mentioned) and running a gasket I cut from an inner tube, on my chev 350, works fine..

 

I can see a little gasket cement I can see, especially if the thermostat is in a hard place to get to. That way the gasket will remain in place

 

Mr Gasket makes an aluminum thermostat gasket with an orange colored silicone insert that is fairly soft. That has worked for me on both my cars with zero leaks.