Berryman B-12 Chemtool Fuel System Cleaner (part #0116) should not be used for fuel as-supplied. For street legal operation, the concentration may not exceed 1 oz/gal in gasoline. For off-road use, our formal recommendation is still the same, but the product can typically be used safely at two to four times that concentration. If you have a situation that would require running more B-12 than that, then there is probably another product in the Berryman line that is better suited for your application.