I used RP HPS 5-30 w/RP filter for 7385 the olm interval in my silverado. Even with the dark color (purple new) the oil look darn good and clean. I know uoa speaks Ive never done so The motor purred at idle and ran smooth. I like it more then the last castor 0-30 which was good. What does everyone think about RP HPS I never hear about it. Keep it coming!