What grade fuel are '05 owners using?

[sjlee]

Originally posted by nolan65
While in Denver the last few weeks, All stations had octane ratings of 85,87 and 90. Here in Ft.Worth we have 87,90 and 93.
Why the change?

Here's an explanation I found on epinions:

"The reason the octane is lower in places like Utah and parts of Colorado is because they're at high altitudes, where the atmospheric pressure is lower. At lower pressure, you can get by with lower octane, which costs less and causes less pollution. "

I found this from CarTalk:

"Tom: And what allows you, Bob, to use lower-than-recommended octane is the altitude in Colorado. Up where you live, the air pressure is lower. That means the pressure in the cylinders is lower, too. So by going up 5,000-plus feet in elevation, you've effectively lowered the compression of your engine, and that means you can use lower-octane fuel without making the engine ping.

Ray: At the altitude where you live, 85 octane is the equivalent of 87 octane at sea level. So, by all means, go ahead and use it, Bob. Along with getting winded more easily, it's one of the fringe benefits of living up there in the mountains."