2006 Pontiac Grand Prix Engine Life

To answer your second question your best bet on that would go to kbb dot com they give prices for dealer and private party sales values they should sell for how much there worth etc. There are so many options you need to put in options condition zip code it's selling in etc to get a price. Your second question now that can vary greatly even from one engine to the next. Working at dealer I have seen the same engine same year gas mileage vary greatly the amount of power it puts out and life of different parts of the engine etc. The main thing is how the engine was treated it's whole life? Was it loved oil always changed when it was supposed to? Or was it abused oil changed whenever the person felt like or they just added oil when it got low.