Trekk

Well, as some of you might of read. I bought a used 04 GTO a few weeks ago. Car facts shows it taken to the dealer very often for it's oil changes and so on. Since hasn't been my car from day 1 I'd like to replace all the fluids stating with the radiator. Mostly because I live in hot ass Miami Fl.

I was thinking about putting in a 160deg stat and just flushing all the fluids. I'm not worried about the warranty or anything. I've just been reading around about fluids and find lots of people fighting over the dex-cool and green stuff. I just want to know what is better (effective wise)to put in the car. It never really gets cold down here, maybe the 40's in the middle of the night from wind chill, but about 75-95deg is the norm around here 95% of the time.
Should I just put more Dex in? can it be watered down more? or should I move on to something else.

This is the first car i have owned with dex-cool it in.

Thanks.