this is a revised update by me on the continued use of using b12 chemtool in my gas tank. at every fill i use 4ozs in the 11.75 gal tank. i’ve noticed the following mileage increase – almost 4 miles, no hesitation & quicker start up. my kia rio 2008 runs as good as the day i bought it new. by the way i just turned 307,000 highway miles on it. i’m truly grateful for this wonderful product of yours.