What's up with 85 Octane fuel?

[jsudar]

Why do we have 85 octane fuel here in Utah? It seems like in a lot of other places (Cali) 87 is the cheap stuff.

Most manufacturer's recommend at least 87, but I've been burning the 85 in my stuff forever. I don't have pre-ignition issues and I run higher octane when I know I will be running the truck hard, like towing, but I am I missing something?

Is there some hidden benefit to running higher octane fuel if I don't have a high compression engine or problems with pinging?

 

[lewis]

It has to do with the elevation. Higher elevation means thinner air resulting in the lower octane level you can use. Thats how understood it anyways.

 

[DOSS]

Other Places.. Cali = Lower elevation

http://en.wikipedia.org/wiki/Octane_rating

 

[Corban_White]

Why do we have 85 octane fuel here in Utah? It seems like in a lot of other places (Cali) 87 is the cheap stuff.

Lewis is correct here. Higher elevation=thinner air, which means a lower octane is sufficient.

Most manufacturer's recommend at least 87, but I've been burning the 85 in my stuff forever. I don't have pre-ignition issues and I run higher octane when I know I will be running the truck hard, like towing, but I am I missing something?

Is there some hidden benefit to running higher octane fuel if I don't have a high compression engine or problems with pinging?

Octane is basically how well a fuel resists ignition. For example, regular would be like dry grass and premium would be like green grass. In other words, premium requires more heat and or more compression to ignite and then when it does it will burn slower. If you aren't experiencing pinging then there is no benefit to running higher octane unless you have a newer car which uses the knock sensors to decide what kind of timing advance curve to use. In that case, a little power can sometimes be gained by using higher octane fuel.



For a more complete explanation, see here.

EDIT: tooelecherokee beat me on the link.

 

[jsudar]

Ok, I've got it now. Elevation was the piece of the puzzle I was missing. It was one of those can't-see-the-forest-though-the-trees things. Thanks.

 

[cheepin]

Yeah,elevation.When we go back to MI.They have either 88 or 89 as the lowest and 93 as the highest.I got just over 34 MPG on a tank of 93 going through MN.fullyloaded with luggage,my wife and 2 teenage boys in our '06 Malibou with the 2.2 Ecotech!