Pure E100 ethanol has a lower vapor pressure (boiling point) than pure fossil fuels, something like 3 times lower. So yea, this pure alcohol can "cook off" at lower temperatures compared to "pure" gasoline. But, in the case of blended fuels, such as E85, the overall vapor pressure of the mixture goes up, because of some chemistry magic.
The storage problem with ethanol-blended fuels is not that the alcohol cooks off, it's that the ethanol absorbs water. When this happens, the ethanol tends to be less blended with the fossil fuel, and separates on its own with the water, typically below the fossil fuels.
Octane boosters are fine, but I don't care for the added cost. If I'm doing the math right, an $8 bottle of booster over a 20 gallon fill up, adds about 40 cents to the gallon. That isn't worth it to me.
The labelling on these bottles of booster can be misleading, and some may argue they're exaggerated. In most cases, the meaning of "points" is generally 0.1%. So the amount of fuel being treated (or boosted) affects how much boost actually occurs.
If we believe the numbers, research suggests it takes 3-ounces of Lucas Octane booster to boost 5 gallons of fuel by 30 "points." or 3%.
- 87 boosts to 89.6
- 89 boosts to 91.7
- 91 boosts to 93.7
- 94 boosts to 96.8!
In California, where fuel prices can be the highest in the nation, the added costs of mid-octane over low, and high over mid-octane fuels is only about 10-cents per upgrade.
And let's not forget, sometime during the 1980s, the US changed how it calculates octane rating. The numbers went down. If I recall correctly, the original rating as RON, Research Octane Number. The new one is called AKI Anti-Knock Index, but still referred to as "octane."
The following link has some great details about fuels and octane ratings:
https://www.goapr.com/support/fuel_guide/
- 87 AKI = 91 RON
- 91 AKI = 93 RON
- 93 AKI = 98 RON
So when I'm running modern-day 93 octane fuel, that's nearly equivalent to a 1970s 98 octane gas. That's pretty awesome, nearly as high as Aviation fuel.
So in my opinion, if you want 93+ octane fuel, you're better off buying the higher octane at the pump.