What to look for when buying an engine.

Things to look for in a running engine include how the oil looks and smells. Make sure it's clean and fairly transparent. That's a good indication it's been changed frequently. Also, take a vacuum gauge with you. Get a vacuum reading at idle, if you can. The stronger the better. Over 20 inches is good. Also, remove the oil cap and check for blowby. All these things are good indicators of the engine's overall health, regardless of mileage.