Is it possible to unseize an engine rather than swapping it out?

I have an 05 Ford Focus that froze up after crushing the oil filter on a mountain road. Oil leaked everywhere. The vehicle was driven about 2 miles after this happened. I have another engine from another Focus of the same year. I'm just wondering if the engine inside the car can be saved.

Sure, but you would have to tear it COMPLETELY down & check every part. In the mean time, the car sits dead. So the savings involved in just swapping out the dead engine is more in the wasted time the car is just sitting. IF you have another engine, swap it into the car to get it working, THEN take your time to inspect the dead block & put it back into working condition.

It might be possible to "rebuild" the seized engine, depending on how bad the damage is. New bearings, maybe pistons etc.

The engine is seized because there has been metal on metal wear inside the engine. The pistons on the bore, the crank shaft on it's bearings etc, until they have bound up,

Just freeing things up won't fix it because metal has actually worn away. It may rattle along for a little while until it beats itself apart totally.

By all means take the old motor apart and insect it for damage, and work out if it's worth fixing. But no "mechanic in a can" is going to make it good again.

You can unseize It but It will never run the same again.

Warning this is not an orthodox method but may work. And I would say you got nothing to lose - get some industrial strength degreaser(make sure it is safe for the metal/alloy of your internals) and fill up the crank case to the top. Let it sit for 24 hrs, take off the oil pan and drain.

Run 3-4 qts of oil straight through it with pan off. Put the pan back on, fill with correct weight oil replacing 2 qts. With your choice of synthetic ATF (Mobil 1 ATF works well). Prime the oil pump if you know how to then attempt to crank - but do not start, pause, crank, pause crank. If it turns over then wait 10 mins then try to Start. You might want to have 40Amps+ plus going from the charger to the battery to give your starter the best chance it got.

If it attempts to start - let it run briefly and listen for any knocks/pings be prepared to do a top end or bottom end rebuild.

If it doesn't crank or turn over after a degreaser bath, drain and refill - try to turn the crank manually back and forth with a long breaker bar then back to crank.

Not really cost effective to try & rebuild an engine that was seized due to lack of oil. Pretty much everything will need to be replaced & possibly crank journals coud be scored bad. Only a tear down inspection can determine yea or nay on saving the engine

Yes, it is. Pull the heads. Remove the oil pan and crankshaft. Push the pistons out. If you can't push them out, beat them out with a sledge hammer, obviously they are ruined. It will be much cheaper and easier to replace the engine than try to salvage the block. Obviously the valves and valve guides will be severely worn in your heads.

Hi it will be less painful overhaul to swap the engines over.

Running with out oil pressure does a great deal in a short time. You drove for longer than i would ever attempt on a car that i wish to kill.