We gave the 2006 Prius to our daughter last year and I taught her how to check it every week and ad oil when needed. She adds a quart of premium oil every week. It’s likely due to the fact that when my wife drove it the oil was never checked and ran it completely dry more than a few times. It doesn’t smoke and it doesn’t leak oil, do you think that oil additive would help? I’m wondering if the OBD will show a fault code for using something that will change the oil viscosity? Last year it did when I was out of 5W30 and used 2 quarts of 10W30