US ethanol is mostly made from Maize (corn) mostly to subsidise and prop up the dreadful US agrigulture industry that is heavily into GM Maize.  The farming lobby is powerful in the US and definately looking for government money from any source.  Of course the oil lobby groups don't want your car to run on maize but on fossil oil so the two lobby groups fight one another.  What the optimum level of ethanol might be for the vehicle and for the planet is not really part of the considerations.

Petrol is comlpex stuff with all manner of things in it.  https://en.wikipedia.org/wiki/List_of_gasoline_additives

 

8 hours ago, trialman said:

 It also does not work well with rubber seals or '0'rings !! hence anything prior to 2010?? NOT BEING SUITABLE FOR THIS FUEL[later cars/bikes use synthetic seals] 

 

What year are you going back to, all rubber seals are synthetic!

Nitrile, FKM (Viton) & EPDM all synthetic  

Also a lot of car/bikes pre2010 are fine on E10

Edited October 11, 20214 yr by suzuki250

Interesting study on E10 and various rubber/plastic etc here:  https://www.hindawi.com/journals/jfu/2014/429608/

There appears to be some effect with prolonged contact but it seems unlikely that most trials bikes would be affected.  Really old bikes have brass carb floats and so on and metal tanks so are almost certainly fine.  I think there is a lot of nonsense in circulation about this subject.  All the same I will stick to my E5 V-Power the bike runs better with the higher octane rating.  Interestingly in the US E85 is used as a very high octane fuel for racing cars.

https://aaoil.co.uk/product/sunoco-e85r/