Coolant drain plugs
 

Can anyone tell me the size allen wrench needed to drain the coolant from the engine?
I don't have the car here, but in the Chilton manual the plugs look like they have a pretty big size hex opening.( I'll have to go buy one along with a crows foot for the pcv valve replacement)

I am going to flush the system and replace the radiator +thermostat, and also install a Trans-cooler.

In there anything else I should do while I have the radiator out?

Any special anti-freeze to use?

Thank You

update
 

By the way, it was 14mm.

Also, they had a wimpy little thermostat in there. I replaced it with the beefier Subaru part.
Trans cooler install was "fun". I put it in front of the a/c condenser. I had to loosen the condenser to fit the cooler and now I can't re-attach the condenser.(without bending things) I guess I'll have to get longer bolts and leave the condenser a little bit loose.

You could get a small piece of metal tubing that's big enough to allow the bolts to pass through it. Determine how far the condensor needs to be pushed back and cut the tubing to the same length and use as spacers. That would be better than risking your condensor and freon.

Beav