Basics

(Typically Conventional Fossil Oil/Fossil Fuel Derived) Gasoline without any Ethanol
- Most Road Gasoline is typically E10 (ie a 10% Blend of Ethanol)
- Some countries use Methanol instead of Ethanol, Ethanol Free Gasoline tends to not have any methanol either however
This has some advantages in Old Engines, and Small Engines , but in most modern Spark Ignition ICE Vehicles, E-10 is fine outside of if predicted long term storage is planned within a tank.
- Certain vehicles can even handle E-15 - E-85 , the Brazilian Ethanol Economy has vehicles capable of E-100 (or Mostly Pure Ethanol, Short of a bit of water and MAYBE a denaturant; citation needed)

Reasons for Using It

Given Ethanol (and most other Fuel Alcohols short of Butanol ) are Hydroscopic, if left to sit, ESPECIALLY in poorly sealed (such as simple vented) containers and/or in Humid Areas, or if exposed to Rain/Dew (Such as an Underground Storage Tank or poorly sealed Internal Floating Roof Tank etc), this can be a major problem
In particular, once it gets to a certain level, Phase Separation will occur leaving a Water-Ethanol solution, and an Out of Spec Gasoline (ie due to lack of ethanol (which was part of the mix that got it “to spec”) it’s Octane Rating and/or RVP etc may have changed enough to cause issues

While it CAN be managed with proper design, again especially with lots of time, Ethanol can dissolve certain seal materials/react with some plastics
Also Corrosion of Metal Surfaces can be accelerated due to the ethanol and/or water itself, or a complex reaction of products produced by those sitting and/or metal interactions and/or Fuel Tank Microbiota

This is essentially N/A for everything, BUT to an extent if you wanted to max out endurance and were super concerned about SWAP etc (such as for a backup generator or some other “critical” use) the higher Specific Energy in the NON-Ethanol Components of Gasoline may be of use
- Akin to the Rationale of Zip Fuels / the Odd Fuels used in Cruise Missiles or (Some) Torpedos/Rockets (Excluding Mixtures using Unconventional Oxidizers etc)

Most Marinas / Large Gas Stations or Truck Stops etc will have Ethanol Free Gasoline
- This is typically also distinguished by a Blue Icon / Pump Handle etc
  - Not always though
- There are also Websites / Apps to locate nearby stations etc

In areas without Available Pump EFG, it may make sense to purchase it in smaller containers
Some Landscaping/Home Improvement Stores will sell “4 Cycle Gas” which tends to be EFG which ALSO does not have 2-Stroke Oil unlike the Premixed 2-Stroke Gas
- Some of this is ALSO Alkylate Fuel which is neat