Is this just a simple drain and refill with new Subaru coolent??

I have looked at other threads that mention engine coolant burping to make sure no air gets into the system and, filling lower reservoir then upper rad? (is this like a rad flush)

Is there a special technique? Is replacing engine coolant better done by a mechanic?

Does anyone have an idea of how much coolant would be needed and cost?

Thanks.

It's simple!  This is how I did it.  It's a bit intensive write up but I've broken it down.

1. Stop by the Subaru dealer and buy a bottle of the "SUBARU" coolant additive.  And also buy a jug of the green stuff.  The orange "long life" stuff will not work in a car that's had green coolant in it.  That is unless you want to spend some time doing a complete flush.  Any green contaminant will ruin the orange stuff.  If you've maintened your car well over the years and never let your coolant go cruddy, then just keep it green and forgo the flush. It's a PIA.  

2. Make sure the car is COOL before doing this.  

3. Open the top reservoir cap (by your turbo) and open the rad cap (at the front of your car) then open the drain at the bottom of your rad.  Have a wide oil pan ready to catch your old coolant.  

[Keep a lot of old towels lying around, the coolant might not come out in a nice stream into your pan if your job goes as well as mine did.  Rather it will run like shower head and get into the frame rails and you'll soon discover coolant pouring out somewhere down the car out of every little hole and behind the front wheels where the subframe attaches(expericed this here).  Now some here will say that you don't open the valve all the way so that it pulls out.  It's one of those simple o-ring sealing units that if it worked properly you'd just make a couple turns and the coolant goes out one hole and is stopped from going out the threaded valve by virture of the threads being there.  Mine didn't start flowing coolant until i unscrewed the valve entirely and pulled it out.  So be prepared to run around cleaning up little puddles of coolant.]

4. Once the car is empty screw the valve back in.

5. (optional) Remove the overflow tank and wash it out.  Mine is a 2007 wrx and it was really easy to do.  

6. Shake the hell out of your additive and pour it into the rad.

 DO NOT PUT THE ADDITIVE IN THE TANK BY YOUR TURBO.

7. Prepare your new coolant.     60 coolant to 40 water ratio.  This gives you optimum coolant for cold winters.     

8. Pour as much as the car will take into both the top tank by the turbo as well as the rad tank.  Some small quick squeezes of the upper rad hose can work a few bubbles out.  Fill your overflow tank to about 1/2 to 2/3 full.  It will be above the cold mark but don't worry your car will natually suck this up into the colling system as it heats and cools and works air out that you can't.  

9. Put the caps on and start your car and up the RPM (not much higher than 2000 will be okay) for a little bit (1 to 2 min) to work air bubbles out, don't let the car heat up.  Shut down and top up the rad.  If you have a friend, you can rev the car and get him to pour some coolant in.  Try to get as much of it the specs ask for as you can.  Check the tank by the Turbo, top it up if you need to!

10.  Take the car for a spin and get it hot.  Let it cool, check both turbo tank and rad, top up as nessary.  Check the overflow tank and add coolant if it's below the cold mark.

11. Take your used stuff to the ECO station for free disposal.

12. Check your coolant levels a week or so later to make sure it doesn't need anymore.  

Man thats a sweet writeup, pictures would have been a +1 tho.

If you want a quicker way to drain the coolant, remove the bottom rad hose from the radiator and remove the rad caps.  Its messy for the first couple seconds but once everything is in place it drains fast and without much spill.

This sounds so easy.
When prepping the coolant (60/40) do you need a special container (Jerry can) to mix with or can you just put 6L of coolant and then 4L of water into rad? (does the premixed coolant take care of adding water?)
Is the overflow that critical to remove and clean? I assume that it is not difficult to locate on a 2003?

I plan to try this over the weekend.
Thanks.

You have to mix the coolant and water first.  NOTE:  Use dionized water $2 dollars at parts source.  Also your car does not hold 10L of coolant and coolant does not come in 6L jugs.  

If you can find Premixed in a 60/40 ratio that should work, but it costs more.  Why spend more when you can get a measuring cup and make your own mix in 30 seconds?  Plus you'll have to buy 2 jugs of premixed coolant to get that the amount you need.  Then you're left with 1.3L of extra coolant lying around taking up space. 

Here's what I would do:

Buy the 4L of good quality green and mix 2.7L of deionized water with it.  You'll end up with 6.7L of 60/40mix PLUS the 250mL of additive for a total of 7L which I believe is what your car holds (too lazy to look up volumes).  

I went last week to pick up some coolant from Rally, annoyingly, they only had the concentrated coolant in 1L bottles. Only the premixed came in the 4L jugs. I just opted for two jugs of the premixed, it's pricey at $21/jug though.

Wally did you have to buy the additive too? and did they have it in stock?
EDJ, I assume I can pick up Prestone at part source along with the deionized water?

Yeah I bought the additive from them as well. They have lots in stock, pretty common thing for them to stock.

thanks for the tips. I did not get to rally yesterday but I hope to make it there tonight or tomorrow.

This might help other people if they wannt give it a go as well. He has pictures of everything.

Jeff me too. every time I walk past by subie I see the 2 jugs sitting there taunting me.

The service guy at rally did not mention anything about a complete flush. But then again I will assume that he thought that I was going to do that myself. (but wait I don't have a certified Subaru flushing machine at home??)
Looks like I will have to call and book an appointment to get this done vs. doing it myself.

Wheeler, do you know of any Green coolant brands that I can buy at crappy tire or else where that will do the trick, I don't want to have to pay more for a full flush. I just want to drain and replace. 

Prestone is a tried and true product.  I used Esso Premium as that's what Centaur subaru sold me when I went in to pick up my conditioner.  I didn't feel like driving to a parts store for basicaly what ammounts to the same thing.

In fact the service rep told me that they only put the superblue in the 08/09's. 

Like I said before, keep up with the changes and you'll never have a problem.  Once every 2-3 years is really not that big of a deal.