The more strong solvent you can introduce into the system, the better off you’ll be. Since you’re going to use the mixed gas in your tractor (as opposed to on the road), you can exceed the regular maximum recommended concentration of 1 oz/gal. Rather than using a can (or multiple cans) of the 15-oz B-12 Chemtool product (part #0116), you might consider purchasing a gallon (part #0101) instead. After that, the only caveats to using this gas mix in the tractor pertain to the fuel line, carburetor(s), and combustion chambers. First, ensure the fuel line is a modern, high-quality material that is compatible with E10 gasoline. Second, the gas mix will have a fair amount of content that will not burn cleanly. This can gum up the carburetor(s) and cause excessive combustion chamber deposits. Consider adding Berryman B-12 Chemtool Total Fuel System Clean-Up (part #2616) to the mixed gas at 1 oz/gal and then again to the tank of gas you use immediately afterwards. Good luck!