Hello Im a 24/7 on call mechanic for my boys. My youngest owns a 2005 wrx 2.0L turbo with around 120K and is having serious issues and I think its safe to say he will be needing another motor. It started out as a simple coolant leak on tstat by pass coolant hose. I replaced tstat while I was there and proceeded refill of coolant.I tried putting in reservoir only but it wasnt pulling out so I filled radiator then filled reservoir to full mark. It would take along time to come up to operating temp and when it did there was no heater, sometimes. Let me say this, it was noticed before all this started that the sound of the car had changed. Dont know how to explain just that it was different more "rough sounding". It was noticed in tstat housing and on old tstat that there was alot of corrosion which later to find out all parties had used wrong coolant. It took probably 20-30 mins at idle to get to normal operating temp and when I tried heater, nothing cold air. Anyway my thinking was maybe air pockets was cause of issues. When he got home he took gown road and heater worked then. He called one night saying it was leaking again and he now has CEL. I pulled codes and didnt record them so cant get real specific but he now had misfire on every cylinder as well as 2 about low coolant or low temp. He said he put low octane gas in it and that might be cause. I thought maybe, cleared codes and he drove for couple days. It had serious engine misfire at Micky Dees yesterday and would barely start and once it did it ran terrible. He then carried to local dealership (not Suburu) but one his older brother works.The car was found to have lower radiator hose that was loose. He fixed and tried added coolant in radiator. Now this whole time my youngest said the car never ran/showed hot but when he cut off that there was some smoke from under hood but not alot. Now the diagnosis the dealership gave was motor fried bc of lack of coolant. Now Im thinking how does a car that never run hot but is now trashed bc it was starved of coolant? Also my oldest said there is coolant coming from everywhere now and that he used 6 gal of coolant when 1st brought in. 1st- is this possible? 2nd- can anyone point me in good direction for another motor and can u give approx cost? Im in central Al. and I know he has found one on ebay less than 50k for $700 3rd- can the 2.0L be swapped with 2.5L? Thanks for any advice....