Just wanted to share a recent used oil analysis on my 2013 Prius C with ~ 173,000 miles on it and ~ 6,900 miles on the used oil. The oil was changed by a local dealer that says they use Mobil 1 or Toyota oil. During the first 80,000 miles of ownership, I always got oil changes every 10,000 miles. Then I shortened the interval to 6 months/5,000 miles for the followng 90,000 miles at the recommendation of a previous dealership I no longer use. I just got the oil tested to see if I could split the difference with an oil change interval of 7,000 to 7,500 mi. It looks like I can. Based on the timing of my dealer's promos, there really is no reason financially for me to extend the oil change interval any longer than that.
