IIRC the accelerated aging gasoline gums test allowable level used to represent 3 months dark storage (no direct sunlight / UV exposure) for 3 months, now I'm pretty sure it's 6 months. Much was driven by military investigation for their needs, especially requirements in Eutope back during the Cold War. Some testing was done here in San Antonio during summers in particular due to the effect of temperature on the reaction rates. It should be noted the gums test is run at point of production, well before ethanol is added at the distribution terminal. Ethanol in and of itself doesn't increase oxidation potentional of the gasoline for forming gums on its own but has its own issues regarding materials compatibility, phase seperation, hydrophilic tendencies, and volatility that ethers like MTBE, ETBE, & TAME didn't have.
I routinely dose my OPE cans with stabilizer because where I store it is not climate controlled and summertime ambient temperatures accelerate the reaction rate. This also means my OPE fuel is already spiked come wintertime. I think it's wise to add antioxidant / stabilizer to any gasoline being stored 3 months or more personally.
