Can I change coolant?
 

My 2207 HHR LT which I bought 1 month ago came with the Red coolant and it's more than halfway gone.

I have about 1.5 Gal of 50/50 Green coolant and 1 Gal Full strength Green coolant.

Can I flush the Red coolant out with a hose and just use the Green coolant?

You should flush it out and recycle the green stuff and refill with DexCool 50/50 (orange stuff).

Did you consider finding out where it is going?

The Green Gals I have are new/unused. I dont want to waste them. It is Red in the wagon that I want to get rid of.
And when I say "get rid of", I do not mean flush it down the middle of the street where kids are playing.
I mean it as a figure of speech without having to write an essay.

Gee, you are reading way to much between the lines.
My point is that neither the red nor the green are correct for your HHR. Only DexCool is.

Red is for Honda, green is for Ford, orange for modern GM. It is written right there on the pressure cap and in your Owner Manual.

If you don't want advice don't ask for it.

When DonBrew asked the question Did you consider finding out where it is going?, he wasn't giving you a hard time. He was asking if you considered why it's down by half. The car should not lose that much coolant. A little is normal. Changing it is a good thing, but you need to find out why it's so low to begin with. Also as said don't use anything but DexCool or a certified DexCool compatible fluid. Using the green just to avoid wasting it is not good for the car's cooling system. The red stuff may already have caused an issue that's making it lose fluid.

My car has had no coolant in it since new. Should I add some now ?

Naaa, you'll only end up worrying about leaks.

MED CHECK FOR CAT MAN HHR!!! :)

Follow the Owners Manual. The Dex/Cool should be changed every 5 years as well.
Lil preventative maintenance will save you money in the long run.

I am not speaking from technical knowledge but I picked up a 2.2L ecotec to put in my buggy and I put in the green coolant 5 years ago and we run these engine at 4000-4500 rpm all day long and beat them up I have not had a problem and my boy is running the red, just saying. I am more concerned for the wifes 2.4L HHR that I would like to be more correct with BUT what is correct and why.