The “northstar” like “hemi” and the like are advertisement gimmicks that may refer to particular characteristics of a motor but may not be relevant to it’s longevity or performance. I wouldn’t hesitate buying a new Cadillac if the motor was your only concern. Not only has the motor been improved in many ways, but like most, is more reliable, economical and better performing. They couldn’t keep up if it wasn’t. Caddys are good solid cars and have always been a good buy IMO.