IF, (this being a rare exception for oil-not usually necessary) your oil in your motor was thick and black, a cleaning-detergent additive would be useful.
The Zinc additives that they tout would not benefit you hardly at all as Captain Caravelle has pointed out. Slick 50 only has powdered Teflon it which does NOTHING for you.
If you get dirty gas, half a can of Seafoam. If you got gas, drove off and accelerated, only to have the car & throttle miss & hick up (water in your gas) -a bottle of water remover (HEET as an example would help. Ethanol blended gas does not seem to have as refined gasoline it from my experience-small flecks of tar float around in it-clogging fuel pumps and filters.
If your vehicle sits for a long time, the red bottle of fuel stabilizer really helps, as gasoline slowly degrades to tarnish- I use this for long deployments.
Stay away from recipes adding acetone or Xylene - you will ruin seals.
The older generation swears by marvel mystery oil, but they also drove older/different vehicles than what we drive now.- I believe that it has a very light oil in it.
Multiple places on the web say that toluene is an octane booster- but it would be better if you referred to experts rather than play chemist.
If you have a catalytic converter, do not use Avgas (Aviation 100 low lead fuel for Propeller aircraft)-even if you did not have a catalytic converter, it has paraffin in it as well, which leaves a tremendous amount of carbon build up in the combustion chamber-they rebuild engines in the aviation's FAA standards after 3 or 5 thousand hours (can't remember which) unlike what you expect to get out of a street engine.