use frequency January 5, 2013 Solutions Central › use frequency 0 Vote Up Vote Down cchiz asked 12 years ago how often do you add B-12 chemtool to your gas tank 1 Answers 0 Vote Up Vote Down chemtooler Staff answered 12 years ago You will add B-12 Chemtool® Carburetor, Fuel System and Injector Cleaner (part #0116) every third tank. Please login or Register to submit your answer Username or Email Address Password Remember Me