panolo
Seldom right...Always opinionated!
I agree generally but just to point out a couple of bits that don't come across very well from your post.
1. all petrol (gasoline) has the same calorific value, high octane has no more oomph.
2. The higher the ron, the 'LESS explosive' it is, i.e the less it will auto detonate.
3. Higher RON fuel allows tiing to be advanced without autodetonation aka knocking or pinking. KNocking is bad, it will damage an engine, but advance timing generally gives more efficiency and power. So premium fuel allows for more power IF the engine is advanced (auto tune will advance the timing I assume? cars definitely do, car EMUs are constantly striving to advance, but have knock sensors and retard again if knock is detected. fill a car (like mine, a modern turbo powered semi performance engine) with standard fuel and I notice it knock and run rough/won't rev and pick up, then it settles quickly but I'll get may 10% less mpg. fil it with premium again and it will take 3 or 4 tank fulls to slowly advance to its max again.
4. Ethanol increases (yep really) RON/Octane.
5. Ethanol absorbs water, if it absorbs enough it separates out as a gel to the bottom of the tank, strpping the RON from the remainng fuel and sludging the lines and carb. Keep the tank sealed and water away and it can't happen very fast.
6. ethanol also attacks and softens some rubbers - bad for lines and carb diagphrams
7. fuel also contains aromatics (benzene ring based compounds). These oxidise over time and form gums and varishes which block carb jets etc. Star tron (which i also use ) etc work by slowing the oxidation process. Star tron also claims to solve ethanol problems....err.....no idea what chemistry it claims to use there.
8. final problem with old fuel is simply the volatile components evaporating. the really volatile stuff is small enough molecules it will diffuse through plastic cans, so seal and store in metal cans. loss of volatiles jut makes it harder to start a cold saw, but still runs ok.
Yes all gas in theory has the same energy per ounce. As I said higher octane allows a larger power transfer by being a more controllable detonation. Ethanol does absorb water but ethanol doesn't need water to separate. Maybe your Euro fuels are different but untreated ethanol 87 starts to break down in about 30 days when we tested it. Aromatics last a considerable longer time in non-ethanol fuels. There is also a variation in brands of fuels. Whether it is BP fuel, Holiday fuel, or Kwik Trip fuel. What they have added in to make it there signature named fuel makes a difference in energy transfer and longevity. If we take a fuel that is sold around here that is called neat 92 which is a non oxy zero additive fuel it stays very close to it's pump form for 10-15x longer than your 87-89 octane pump fuel. The reason isn't because it has 5 more octane, it's because it is a more pure form of gasoline.
You can run old broken down fuel but it isn't a guarantee that it will run ok or at all. It's simple enough to do the gerber test in your garage. Take a few gerber food jars and store different fuels in them. Keep them out of the sun and in a semi controlled area. Strip a little out and ignite it on the cement. The purer fuel will win at every stage whether it is at 1 month or 2 years.
Startron is a great product and what I use as well. In theory starton keeps ethanol from separating from fuels by absorbing water before ethanol can and tightening the bond between fuel and ethanol. Ethanol and fuel don't just mix. It's a forced marriage and the second that they can get divorced they will and it happens sooner than later.