I have hired a DD guy to do a code read on an 8V92T that is in an older Liberty. My question is, just what am I going to learn from this adventure? I think it will show a history of engine temps and RPMs, but what else should I expect for my $75 bucks? And, what would be acceptable numbers? At what point would you say "nope, I don't want an engine that has run ---degrees or over ---RPM." Any guidance here appreciated.