octane rating and engine performance
In Texas, the minimum octane rating is 87. On a recent trip to Glacier, I noticed a lot of the fuel in states like CO, WY and MT, the octane was 85, and you had to buy the mid-grade to get 87 and abov...
Forum Discussion
85 vs 87:
"Octane measures resistance to knocking, ergo, higher altitude means you can use lower octane. If your car runs fine on Regular (87) at sea level, it should run fine on Regular (85) at high altitudes. It's not an exact equivalence, but it's good enough for a car."
Ethanol:
"In terms of its octane rating, ethanol has a rating of 113. Fuels with a higher octane rating reduce engine knocking and perform better. ... When you mix 10 percent 113 octane ethanol with 85 octane gasoline it increases the octane two points to the normal 87 octane most consumers use."
"Octane measures resistance to knocking, ergo, higher altitude means you can use lower octane. If your car runs fine on Regular (87) at sea level, it should run fine on Regular (85) at high altitudes. It's not an exact equivalence, but it's good enough for a car."
Ethanol:
"In terms of its octane rating, ethanol has a rating of 113. Fuels with a higher octane rating reduce engine knocking and perform better. ... When you mix 10 percent 113 octane ethanol with 85 octane gasoline it increases the octane two points to the normal 87 octane most consumers use."
