Quote Originally Posted by gpbastard View Post
you might want to put in a new thermostat. you can use dex-cool, but you have to change it every 3 years or at 50k miles. under no circumstance leave it in for 5 years or 150k like GM say's. you,re asking for trouble. you can also use a universal coolant as well. that's what i use.
it sound's like your thermostat is probably stuck open. have you put in a new lower intake manifold gasket yet. those engines eat them up after about 100k miles.
your post was a bit cryptic but are you losing coolant?