I use the PSD white bottle all year long and once a year I will use the Amsoil version that is supposed to be a little stronger.Mike9, its advisable to only use the 911 IF you gel up...but you can use Power Systems fuel supplement (or other brands) to PREVENT it from gelling...and to lubricate the injectors and pump and so on.
911 can cause damage if used often or consistently. Its not designed to be used as a preventative.