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I just moved to Denver CO and noticed that for regular, the octane is 85 instead of 87. Will this be an issue to use in my BKO?
 

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the change in elevation allows lower octane. If you ran 87 @ sea level, 85 @ 5000 ft will be fine.
 

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I run 85 all the time, even have my timing bumped up a little. 85 does have 10% ethanol everywhere here, but there are a few pure-gas stations around that have 87 or 88 octane pure-gas. I know of two at least in the great state of Northern Colorado.

I would stick with the 85 though. 87 or 88 octane pure gas runs nice, but is expensive and only slight gain in MPGs (negative return on your investment).
 

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It should be fine with the elevation change and such.
I know in my motorcycle (a 2000 GL1500 Goldwing) riding two-up and towing a trailer ran it without ANY issue in Utah, and it also calls for 87 from the manufacturer.
 

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Here in SD we've got 85. I still used 87 as when I used 85 I'd get knocking when going up hills. BTW, this was before I did the Sixlitre tuneup.
 

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Air loses density as altitude increases, which results in lower cylinder pressures (like lowering compression ratio) so an engine that requires 87 octane at sea level will tolerate lower octane at elevation.

In addition to this, most engines will respond well to additional ignition timing and a leaner air/fuel ratio as elevation increases.
 

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The lower the octane, the higher the energy content & the better burn. There's probably no ethanol in it, for the octane rating to be so low.
very few pumps are ethanol free up here.
 

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So just out of curiosity can I run 85 in the bronco here in Maryland? If so would it hurt anything.
 

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So just out of curiosity can I run 85 in the bronco here in Maryland? If so would it hurt anything.
you probably cannot get 85 @ sea level.
 

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Thought I'd throw this in. In Florida at sea level Regular is 87, you can't get a lower octane here.
 
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