All depends on numbers surely?
You buy a car, engine has issues, new engine installed........you effectively get a brand new motor to run in for the price of a used one. Getting a new engine is great and no worries about the other one being opened up - engine replacement isn't that complicated as it will be in a crate ready to be connected up, much rather this imaginary 18yr old was hooking up a new one than taking the head off and rummaging around inside it.
Or buy a used one not knowing how that one was treated.
I would keep the courtesy car until yours gets its new engine then treat the new engine as a new car.
You buy a car, engine has issues, new engine installed........you effectively get a brand new motor to run in for the price of a used one. Getting a new engine is great and no worries about the other one being opened up - engine replacement isn't that complicated as it will be in a crate ready to be connected up, much rather this imaginary 18yr old was hooking up a new one than taking the head off and rummaging around inside it.
Or buy a used one not knowing how that one was treated.
I would keep the courtesy car until yours gets its new engine then treat the new engine as a new car.