Throughout your life you will undoubtedly own numerous vehicles. At some point and time you may find yourself in a position where you have to replace the engine in one. When this eventually happens you will have to decide what type of engine you want to replace the original one with. The two main choices available these days are either a second hand unit or a reconditioned unit.
If you are not planning on keeping the car after it is repaired you may elect for the slightly cheaper option of a second hand engine. Bearing in mind you have no way to tell what the actual mileage of the engine is or the driving habits of the last owner, that lends the second hand option better to a repair and sell scenario as most second hand engines come with a short term warranty if any.
If you plan to keep your vehicle you should seriously consider the benefits of replacing the faulty unit with a reconditioned one. In general a reconditioned engine is virtually brand new inside so in effect it has zero miles on it and it will have the potential of having the longest life span if looked after properly.
A standard reconditioned engine has had quite a bit of work done to them in order to be able to offer a longer warranty and is a smart choice for those who take pride in their vehicles and would like to keep them for as long as possible. At a minimum machine work will have been done to the engine block and cylinder head in order to ensure they have flat mating surfaces, cranks are machined, polished or replaced as necessary new bearing sets will have been installed in both the connecting rods and main journals to ensure optimum oil pressure can be achieved, the pistons will have been fitted with new piston rings to create a positive seal in the cylinder chamber, cylinder heads will have been pressure tested to make sure they do not have any internal cracks, New oil seals will have been fitted to make the unit oil tight after all is reassembled the engine should be fit for purpose and provide a dependable replacement for your faulty unit.
All reconditioned engines should be "broken in" gently. This means that you do not want to hop in a vehicle with a reconditioned engine in it and immediately go out and put your foot to the floor on every occasion. The break in period is very important to the longevity of the new engine. At this time all of the new metal components ( rings and bearings) will slowly wear themselves in to their adjoining parts so all surfaces will mate and work optimally in the future. If the break in period is ignored you can actually shorten the life of the replacement engine and cause conditions where the oil pressure will be too low or the piston rings will not seat properly causing the replacement engine to burn oil.
At the end of the day, if you choose a reconditioned engine as a replacement for your original, it can last you the life of the vehicle if it is taken care of properly.