High octane fuel is not required at high altitudes.  In fact, if a given octane is required for your vehicle at low altitudes, you can use a lower octane at altitude.  The regulators and the oil companies know this.  Look at the pump next time you are in Colorado, West Texas, Wyoming ....... .  The standard for regular grade gasoline at low altitudes is 87 octane.  In the places I named, regular is 86 or 85 octane.  It burns just as slowly (meaning better) up there as 87 octane does down low.  mcneely

---- Steven Johnson <sjohnso2000@GMAIL.COM> wrote:
> On those kind of trips (cross-country or long distance)  I do use 91 octane
> as I understood that it tends keep
> the heads slightly cooler.
>
> Good question,
>
> Steven
> 91 Westy
>
>
> On Mon, Jan 20, 2014 at 2:18 PM, Robert Stevens <mtbiker62@gmail.com> wrote:
>
> > On Jan 20, 2014, at 2:07 PM, KevinPGilleran <kevin@GILLERANENERGY.COM>
> > wrote:
> >
> > All,
> >
> > On my last trip out to the Grand Canyon and then circling clockwise around
> > to Zion I found that my 1991 westy had problems with what I can only
> > imagine
> > is the altitude (4970 ft at Kanab Utah). I could barely get the van up to
> > 50
> > miles per hour the entire time we were at elevation. But once we dropped
> > back down into California and were back on highway 5 (400 feet or so) we
> > were back up 70 mph no problem.
> > Any ideas of where I should start on this issue would be much appreciated.
> >
> > Your '91 says it requires 91 octane on the fuel cover door IIRC?
> > Is this a change in altitude performance for your van?
> > Do you use 91 octane?
> >
> > My performance suffers at higher altitude as well, but then I have an
> > engine
> > conversion (Subie) and always use 91 octane. I guess I wonder if this is
> > the
> > first time this has happened in your travels at altitude, or if it's just
> > been a long
> > time since you were driving your van at that altitude?
> >
> > bob

--
David McNeely