An observation for FWIW, I was using some cellulose filters while doing the clean/rinse cycles of an ARX treatment and noticed my oil pressure was running slightly lower than normal. I have an electronic afterrmarktet gauge installed and would normally run about 38 psi at 1500 rpm and about 50 psi once I got up to 2000. While running the cellulose filters I would only get about 30 psi at 1500 and 40-45 at 2000. Difficult to judge exactly as the gauge only has 25 psi increments with a mark in between. Now that I'm done with all that and switched back to the more expensive synthetic filters, my oil pressure is back to what it was before too. I know synthetic is supposed to be better but was surprised to see that much of a noticable difference between the two medias.