Do I need to use rtv sealant when changing my thermostat in my car?

A light application of RTV sealant will not cause any problem used with the o-ring or paper gasket that comes with the thermostat. Just remember the two things that cause trouble with RTV. One is that too much is not better, and the second is that you will have to spend additional time the next time cleaning the RTV off.|||you dont have to use it.some gaskets seals themselves.now mine has a 0ring and dont require a gasket.|||if there was no gasket when you removed the old one then possibly. replace gasket if there was one. if you use rtv be sure not to get it inside of thermostat housing as this could block coolant flow. if ther is any doubt, contact a local mechanic|||You can use a little bit to be sure it seals but most of the time you don%26#039;t need to