Oil and Fuel Additive Cleaners

I use an additive in my diesel trucks but not in any carbureted gas engines I own. They all run premium 93 and the 2 old ones get non ethanol. Whenever I do a trans flush the used fluid goes back into the fuel tank a qt at a time until its gone. The truck seems to get better millage while burning the trans fluid mixture .

 

Thanks. I just replaced the tank too. I will probably burn through this tank in the next week or so.