1988 Dodge Grand Caravan V6 3.8L Engine Rinse Phase 1st Filter of Rinse phase 2nd Filter did not have anything to speak of in it ST16 (e-core) filter 1500 miles on filter/oil Mobil Clean 5000 oil About 148K on Engine when filter changed As you can imagine. Engine with more power. Smoother idle. etc. Valve cover was removed pre clean phase, post clean phase, and post rinse phase with only slightly improved "clean look." Actually, I thought they were unremarkable myself. Varnish still there, but just lighter. Also, there were several short runs of 2K OCI's due to oil turning black quickly prior to Auto-RX use. Purchase of minvan at 138K. Those oil filters were cut open also. But nada in them, just very dark.