Originally Posted by
trism
Every state has the same fuel.
Regular ULP is no lower than 91RON. Ethanol has a RON of 109. so when blended with ULP in a 90/10 mixture, you end up with about 94RON. HOWEVER, its not always a perfect 90/10 mixture. That 10% is the MAXIMUM amount of ethanol that is in the fuel. It could be anywhere from 1% to 10%. Therefore, the RON of E10 will vary between 91 and 94RON
Then we have 95 and 98 PULP, which is ethanol free.
The 100 octane you see united selling is still E10, but its mixed with 98RON.
SOURCE; Have managed servo chains.