I did not have much faith in "Fuel System Cleaners" but I soaked a 17 year old injector in a clear glass with the B12 Chemtool and watched as the grime disolved before my eyes. Within just a few minutes, i saw the grime slowly falling to the bottom. The metal outside of the injector looked almost new. Try this with your Shell V Power fuel system cleaner and let us know how well it works.