If stored in plastic containers, fuel will lose the small low molecular weight molecules, becasue they pass easily right through the plastic. This will cause a drop in octane rating, and leave behind the large high molecular weight molecules that will turn to varnish and scum. On the other hand, fuel stored in sealed metal containers can litterally last for years!!! Ok, so I store my fuel in metal containers and I run Klotz Octane Booster which has a fuel preservative, but WHAT ABOUT THE FUEL LEFT IN THE QUAD'S PLASTIC FUEL TANK???? No matter what, it will gradually lose those small molecules, and I don't think we are all prepared to drain our tanks after every ride.... I always top up my tank after a ride, to reduce the amount of surface area in the tank where oxidation and evaporation will rapidly take place. I can't say that I have noticed any drop in octane (no pinging) as a result of long term storage in the quad's fuel tank, and I have not had any gummed up carbs or fuel injectors in a decade, since I began running Klotz. Nice that my dual-sport bikes have street legal metal fuel tanks! Not exactly light weight, however.