I'm not doubting you as there are different formularies of Pump gas depending on Season and Company.
There are includes varying degree of Pump Gas contaminates cause during the production, transportation and storage of Pump Gas, (Such as Gas Station and Tanker contaminators).
We used 87 Octane with a "stated" amount of 10-15% Ethanol at the Pump.
With our situation we actually removed the OEM Gas Tank and an Aftermarket Gas Tank for a 64 Chevy Truck to test the affects of today's pump gas.
We put about 32 ox of Unleaded Pump Gas into Both Tanks.
After 48 hours we used a Bore-scope first with the tank with fuel, then drained each Tank.
The Bore-scope showed significant corrosion in BOTH Tanks at the top of the fuel level line in each Tank (so we surmised that the presence of Oxygen accelerated the Corrosion with Ethanol Fuel..
We also needed a third tank so I used a small engine tank for a Third Test.
We used Ethanol Free VP 94 Unleaded Racing Fuel.
We checked it at 48 Hrs and No Corrosion.
We then let it se for 30 days, (like you would for a unused 2nd vehicle) and No Corrosion or observed and/or Fuel Degradation present with the VP Fuel.
Afterwards I found this Oak Ridge Lab tests on Ethanol Fuels and corrosion that somewhat validated out simple tests.
This report outlines how; a type of Construction Material Used; a Water Content in Fuel; and the specific Ethanol Concentration causes varying corrosion events depending on base condition and concentrations present;
ORNL/TM-2013/143 May 2013
Oak Ridge Laboratories
Engine Materials Compatibility with Alternate Fuels
There's also a ton of related articles from SAE.
Here's one explaining Ethanol Fuel induced Corrosion on Fuel Pumps back in 1997
Surface Corrosion in Ethanol Fuel Pumps
Enjoy
J
Lifetime Member
Society of Automotive Engineers(SAE)