"The owners manual says something along the lines of every 3 months, but that was back in the day of poor quality oil."
Actually oil quality has not changed since the car was built. Multigrade oils (non synthetic) are still the same as always. Oh, there are more choices, but the oil has only changed to meet manufacturers \ government specifications. the oil change interval is based on oil getting dirty, not about it breaking down, unless you are driving on an endurance run or race track. For the older cars, emissions specs have changed the oil composition more so for flat tappet cams, so actually the older oils are better.