All gasoline has detergent additives, Top Tier just has more of the same additive. To turn the minimum EPA gas into Top Tier requires adding just 34 ptb. That is per Keropur AP 205 additive’s documentation.
That is worst case, assuming like Top Tier likes base their claims on, that non Top Tier gas sold is the EPA bare minimum detergency and not one extra drop of additive.
To give Top Tier the benefit of the doubt, for any gas you can just add 34 ptb more of the same Keropur additive and turn it into Top Tier. That is 34 pounds per 40,000 gallons of gasoline, or one pound per 1,176 gallons. That is one ounce of detergent additive to upgrade 74 gallons of gasoline to Top Tier.
To compare that to Techron fuel system cleaner which contains 30% PEA then three 20-ounce bottles contains more than a pound of PEA, ignoring all the other, non-PEA detergents in Techron. Therefore 3.75 ounces of Techron by weight contains an ounce of PEA that seemingly is enough to turn 74 gallons into Top Tier. One ounce by weight then couldturn a 20 gallon tank of any gas into equivalent of Top Tier. That is assuming a pound of Keropur additive is as effective as a pound of pure PEA, which is debatable.