High Octane Gasoline

[Gary Allan]

The difference is typically limited to drivability or "performance". I would wager that two identical cars (or the same car with different fuel sources) spec'd for 87 would attain different ET and trap numbers with different fuels. I doubt that they would get any different fuel economy on an economy test. This was more apparent before knock sensors (my newer jeeps still don't have one) when you had an engine with the air on ..in high temps in variable load situations. The thing could feel like it was carrying on like a coffee can full of rocks and couldn't get out of its own way. Switching to premium would smooth out the combustion process.

Mild knocking under load is considered evidence that you're getting the maximum benefit from the fuel in terms of efficiency.

 

[Ross]

Where I live, North Dakota, Our lowest octane fuel 87 does not contain alcohol. The mid grade 89 does contain e-10. It depends on the station for the premium 91. Some stations do and some don
t cotain e-10. The vast majority of the 87 octane in this state does not contain alcohol. Whether e-10 makes a difference in milage or not, I am unsure. As far as price goes, our midgrade is always the cheapest by about 0.05 over the regular grade 87.

 

[Whimsey]

Originally Posted By: Ross
Where I live, North Dakota, Our lowest octane fuel 87 does not contain alcohol. The mid grade 89 does contain e-10. It depends on the station for the premium 91. Some stations do and some don
t cotain e-10. The vast majority of the 87 octane in this state does not contain alcohol. Whether e-10 makes a difference in milage or not, I am unsure. As far as price goes, our midgrade is always the cheapest by about 0.05 over the regular grade 87.


You lucky b**tards! ALL our gas in NJ contains ethanol. With "real" gas I got 21 mpg, with MTBE oxygenated additive I got 16 mpg, with ethanol I get just under 14 mpg! It su*ks! The worst part is ethanol actually increases NOX emissions and does NOTHING to clean up the emissions of a modern computer fuel injected engine. It was intended for carburetor vehicles to help cold start emissions. It's another government boondagle that will not die!

Whimsey