Since Ethanol is used in regular gas now, does that mean the Octane level needs to be adjusted? Would ethanol increase the octane?

 

Ethanol can and does increase octane. In Iowa, we have three octane grades: 87 octane regular, 89 octane with 10% ethanol, and 91 to 93 octane premium. I suspect the 89 octane is 87 octane with 10% ethanol.

If you see 87 octane with 10% ethanol, I think it's likely they started with 85 octane gasoline.

Dont worry, the number indicated on the pump is correct.

 

E10 has been in use for more than 20 years in parts of the country. You don't have to do anything special to use it.

Steve

 

They blend the fuel to produce the octane on the pump label.