PFTE hasn't been under patent protection for years. Any number of cookware makers have been using it as a nonstick surface without paying DuPont anything or even calling it PFTE. Many of them have excellent name recognition - like T-Fal.
As for Slick 50, there was nothing that really proved that the stuff did anything useful. I got suckered into trying it out in the early 90s. The shop that did my oil change was willing to pour it in. The engine itself was OK, but after a few years I noticed some hard crusty stuff forming near the filler hole and on the filler cap threads. It was really odd when Quaker State bought them out. I also remember Slick 50 synthetic motor oil. It didn't claim to have any of the PFTE additive, but was an API licensed motor oil with the donut and starburst.
The current Slick 50 oil treatment doesn't claim to contain PFTE or any kind of solid.