Good point. Considering that I bought her in Aug 2012 and have only put 4.5K on her, that means the prev owner may have had the change done months earlier and I know he lived close to work too. So it may have been as much as 7000 mi and 2 years since the last change. 3500mi seems pretty short even for regular oil but I am definitely on the "once a year" schedule with my vehicles unless I take a long trip.