OK, when changing the coolant in my '03 GT sedan after 35,000 miles.  I wanted to open the block plugs to get it ALL out.  However even with a 1/2 breaker bar they will not budge any ideas?  Also the coolant "green stuff"  looked alright but therewas a grity sludge in the bottom of the rez tank!  I was alarmed but remembered I did add the magical SOA additive last chnage.  Could it be the result of that? 

 

My plan was just to flush with maybe six gallons of distilled then, refill with 50/50 distilled and Prestone Silicate and Phasphate free?  Head gasket slightly weeping so though a flush might be pushing it.

I've never heard of anyone removing the freeze plugs just to remove coolant!

Why bother? Any small amount that remains is still antifreeze.

Buy a radiator flush kit from your auto store, remove t stat from housing, reattach and add a garden  hose, if you have somewhere safe for the water to drain and not create a hazard. If not, then just add through upper radiator into the block.

The weeping of this series of EJ is a known issue. Subaru just says to add the "conditioner" (aka stop leak) and monitor your fluid levels.

 

O.

Dont remove those plugs. If you get them out, chances are (murphies law) they will leak. A garden hose flush works well, espcially with your low mileage.  Use a good premix to refill the system after allowing as much tap water to drain out as possible. Refill the system with the car running.