I used Arco Graphite a lot, years ago. It was a good oil. Had a friend who knew one of their tech people. Seems Arco had been experimenting with graphite for several years before finally perfecting & marketing it. They had found a way to permanently suspend the graphite particles in the oil. It was a very slick oil. The only problem I ever had, was putting it in an old 6 cyl '64 Ford pickup. After I started using it,a few of the lock nuts on the valve lash adjustment screws started backing off. After I replaced them, I had no furthur problems. And as far as oil filter problems, I or no one else that I know of, ever had a problem with the oil filters clogging up. I think it was one of the best oils at that time. The reason I quit using it, and I think the only reason it didn't sell well, was that it was very nasty. Seeing it black on the dipstick was one thing, but getting it on you was even worse. Changing the oil was a very nasty job. You couldn't just wipe it off your hands with a rag, you had to really scrub with soap and water to get it off your skin, and it would just about ruin your clothes, if any accidently got on them. And if you spilled any on your concrete driveway, or if your engine had a leak, it was very hard to clean up.
Ronnie