High Octane Vs. High Altitude

[Flated]

Anyone know how octane requirements might relate to altitude? Sure, less O2 means squeaking by with a lower rating. Much of our driving in the Rockies is at 5000', and with my old iron lower octanes run fine, even in my '66 Goat at 10.75 compression. I'd guess 91 would work ok with a GenIII V8, if a switch was made to better stuff should one venture down into the flatlands. I'm used to tuning to a ping, but this modern technology renders my medieval techniques less than appropriate! Thanks.

[95LS400Bob]

We live at 4400 ft and can get away with mid grade. But our Lexus on regular has a spark knock when first starting it and a power decrease with regular. Only reason we found that out was the wife put in regular by accident. The computer will lay the timing back if actane is not up to snuff...and mileage result amy suffer enough to offset any savings in fuel cost.

[VBdenny]

With fuel injection, altitude makes no difference as the computer compensates. Not like the old days with duel carbs on a TR4A up the Rocky's.