I saw my first OBD fuel saver scam device IRL today…

[D60]

Found this seemingly credible and somewhat scientific explanation of the moth ball thing:

https://www.eng-tips.com/viewthread.cfm?qid=29471

I mention it only because the device mentioned by OP is largely the digital equivalent.

 

[Malo83]

I still have magnets on the Silverados steel fuel line going into the Q jet.

 

[Yah-Tah-Hey]

I remember that one . The oil companies bought the Patent so it wouldn't put them out of business .

My dad believed that one to the end.