I went to change the termostat in my truck. It looked like it didn't have a gasket before so I cleaned up the surface of both areas and just used the rubber seal I bought for it. Which is what it looked like what was on there before. Well it leaked badly. I had also bought a gasket. So my question is this, I have permatex ultra blue and # 2 form a gasket. Will ether of these work good or should I go back to town and get the one for termostats. Thanks so much. John
Your parts supplier can tell you if it uses a rubber seal around the outside of the thermostat or a paper gasket, if gasket type ensure that both faces of the housings are clean and the top housing is not cracked, if this is ok, any gasket sealant will be fine to help seal it up.