When my plane was new in 2002, after the initial run-in, it used to burn about 1qt in 15hrs. Later on, for most of the years, it was doing 1qt in 8. This then worsened considerably after a tight succession of ~FL200 flights. Using the Mobil 1 0W20 method I got it back to 1qt in 5hrs, and an overhaul reported no unusual conditions inside. My new engine started off 1qt in 1.5hrs (normal) and over...