Scenario is my wife's 99 Grand Am, 2.4L 4 cyl, 60k, the subject of my UOA experiments with different filters. Both UOA's were very good. She bought it used with 29k, nothing but *Mobil 1 every 5k* since 30k. Just for kicks I ran some ARX at 60k for 1500, oil still looked kinda gold coming out. Then the rinse cycle for 2200, both with Havoline 5w-30.  Just finished changing the rinse oil with 2200 miles *and it looked absolutely like tar.* I'm sold. Now 1300 miles with Max Life to get to 65k and back to Mobil 1.

-- Jon O'Data