So I live in Calgary, Alberta (3736 feet above sea level). I have a Mini Cooper on order, due to hatch in 6 weeks.

I have seen a couple of notes about using a lower octane level when at high altitude. For those of you with your nose in the clouds, what has been your experience?


Run 91: just like the book says
Run 89: runs just fine
Run 87: runs just fine

 

At 2,500 feet elevation 90 octane is roughly equivalent to 91 octane at sea level for assuring against pinging (pinging = the pre-ignition which causes that clattering sound as you accelerate). Another 2,500 feet allows 89 octane (New Mexico, for instance).

Our engines want high octane for best performance. I've tried mid-grade and I noticed a little degradation in power, although I do wonder if I'd have noticed any difference at all had someone else filled my tank with mid-grade and not told me they switched me from my regular high octane.

 

I live at 5200 feet. 91 octane no pings. I've been up to 7200, no pings. Wait for posts from Mini in the Mountains when they go up Mt. Evans to over 14,000. That should answer the question!

 

I'm at 7000 feet and get to 10,000 feet fairly often. My experience is with the R-52 but is probably relevent.The car won't ping due to the electronic controls. The loss from lower octane fuel is in efficiency as the car retards the timing (and who knows what else to cope). From my experience, almost totally without any metrics but the average consumption reading on the dash, I have a small loss using 89 octane fuel (E-10 at a local alternative fuels station) but a significant drop in expected mileage on my commute using 86 octane. I usually put in 91 octane, the highest normally available at most stations around here or, if I use mid-grade, give it a shot of E-85 to boost the octane (always being sure to keep the total ethanol level below 10%.