What does it take to make 20k mile oil?
One of my fravorite You Tuber's, Jason Fenske, at Engineering Explained gives us an inside look at what kind of R&D it takes to make a 20k mile oil. Notice the 500k test miles they put on the Silverad...
Forum Discussion
I used Amsoil extended oil change intervals on a Honda and a Toyota. I changed it yearly which was 12-15k. I never had any concern about the oil but about suspended dirt that the high flow stock filters had no chance of removing. I used bypass filters and the oil appeared clean all the time and never used a drop. Dirt is the wear culprit. I wouldn't go 20k without a bypass filter.
