Re: Fuel stabilizer in bulk?
If you look on the Stabil website, they specifically recommend using the RED for long term storage and the BLUE/Marine for day-to-day use in marine engines. I would say the OP is using the products as the manufacturer intends.
I've been running red stabil with every tank in my boat. There may be times when it doesn't run for a month, and at the end of the season, I know the fuel, including that in the carb, is protected. In addition, the red product is 95% isopropyl alcohol, which acts as a binder to keep the ethanol and any water in solution. That said, the blue is actually cheaper if you follow the recommended dose, so next year I will run blue until september and then switch back to red for winter layup.
And yes, the small bottles are a rip. If I remember right, the price per gallon nearly doubles with each successively smaller bottle. Apparently the stuff has a shelf life though, so you can't buy more than you can reasonably expect to use. The goodies that make it work (the 5%) are actually antioxidants that act like a sacrificial anode. They bind the oxygen before it has a chance to work on the gas, so an open bottle will use itself up over time. The website says to look for a color change.