I just finished an ARX rinse with Delvac 1300S, cut my filter open and no deposits were in the media. Previous oil was GC, 4X at 6 month (11k) intervals. The car did have dino in it for first 30k, Synpower/Rotella Syn(G-IIIs) for 20k and GC for the last 4 long intervals. So, no deposits were there for ARX to remove. My issue is now... do I adopt a no-ester oil plan for my seals, I like Delvac 1300S and Rotella Synth, or go back to my 7 case stash of GC...at a shorter interval, like every 4 months? Sludge is a non-issue.