gas for high altitude

[Interstate]

I was flippin' through the manual tonight when I can across this:

"We do not recommend the use of gasoline labeled as "Regular" that are sold with octane ratings of 86 or lower in high altitude areas."

Living in Albuquerqe and Santa Fe at 7000-10000ft, I'd say that qualifies as high altitude. Since New Mexico is a poor state, all there is is 86 octane as regular. Should I go to mid-grade 89? (is it 89? I'll have to check) I know I can't switch to premium as I've been scolded here before for using it.

 

[Ray Lobato]

Are you having problems using 86 octane? I wouldn't think so.
I normally use 89 octane in my Passat, but was in Albuquerque just recently and used the 86 stuff. I couldn't disern any differance.

 

[Interstate]

I don't really notice anything, but i'm not really sure what I should be looking for.

I'm doing something other than what the manual recommends, which kinda worried me.

 

[MrShorty]

The main thing to be "looking" for is spark knock and whether you're under warranty still.

 

[Interstate]

What are the signs of knocking?

 

[Ray Lobato]

Knocking is predetonation, which means that the gas in the cylinder is igniting before the spark plug fires. Is it miss firing (Knocking)? Your engine will not run smoothly, but will run rough. If this is happening, then you should go up in octane, but if it isn't, you should be fine.

 

[Interstate]

Well, the other morning when I was letting the engine warm up* a little, I noticed that the entire vehicle was somewhat vibrating. I figured it was just the engine being normal as it's just a generic V6. Maybe I switch to 88 octane to see if there's any difference.

*The manual stated that it's not required to warm up the engine.

 

[MazdaGreg]

As far as running 86, I live in Denver and being that the lowest altitude i'm ever at is about 5500 ft, i run 85 in mine. As long as you don't have the spark knock, you will be fine. It will sound like Marbles loose in your engine compartment. if you don't hear that, roll with it.

The reason they use lower octane up here is because with the lack of oxygen and air density, the combustion chamber is not so volitale. Therefor you are also sacrificing horsepower just by living where you do. But what this means is you can run the lower grades of fuel, and still just be fine.

Just wait until you get your Explorer to sea level. When i go to texas or california, i cant keep the rear tires from spinning. Up here, i really have trouble getting out of my own way sometimes.

Good Luck,

 

[Interstate]

Cool, thanks for the info!