Quote:
Originally posted by jinno@May 9th 2004 @ 12:06 AM
Yup, Colorado sells 85-octane as its "regular" unleaded
gasoline. Mid-grade (or plus) is 87, and Premium is 91
(at least where I live).
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You probably know this already - but effectively, octane increases with elevation.
The reason for this is most easily explained by understanding (VERY basically) that octane is not really the ability of fuel to burn, but the ability NOT to burn.
As octane goes up, the fuel burns slower - not faster (this is a gross oversimplification, but it serves to illustrate...)
As altitude goes up, there is less oxygen therefore less tendency to burn - thus, higher effective octane. Therefore, a lower octane fuel (rated in a lab closer to sea level!) will burn as if it were a higher octane at altitude.
Coming down of course gives the reverse - but I really think a loss of two points really won't matter all that much. If you really want, putting in a mid-grade before the trip might be reasonable.
Jack