[Manitoba Keith]

Just wondering what Octane Model 2 users, that live at elevation like Colorado, Utah and higher AZ, use. I have been told that due to their elevation, 85 was the same as 87 is for us flatlanders. I think those areas are about the only place I have ever seen 85 as "Regular" gas.
Would really like to know what a Model 2 Volt user uses in those areas as I will be driving through there using the ICE.
YES, I know the manual says - "97" BUT, are there exceptions for higher elevation.

 

[FI Spyder]

I believe the refiners use different additives for high altitude locations like they do for summer and winter blends.

 

[somms]

YES, I know the manual says - "97" BUT, are there exceptions for higher elevation.

87 minimum for the Gen2 according to 2019 OM...

FWIW: I've been using 88 ethanol(alcohol)-free fuel for years on my Gen1 with higher octane requirement w/o fail at these higher altitudes!

 

[alfon]

you tube post mpg Gen 2 Volt:

https://www.youtube.com/watch?v=0TsMOCL80Ws

At 7:46 you can see that they used 85 octane for the test. I believe they are in high elevation. They still obtained over 40 mpg at 75 mph in gas only mode during winter or cold conditions...

 

[Manitoba Keith]

FWIW: I've been using 88 ethanol(alcohol)-free fuel for years on my Gen1 with higher octane requirement w/o fail at these higher altitudes!

Thanks for your reply.
So, you are using 2 points lower than your manual says to use!

I am thinking I would at most use 2 or 3 tankfuls of the 85. There isn't that much difference in price between the two ($0.20?) so for 25 gallons it might be $5.00. Not really worth taking the chance and using lower octane. I know my Altima hated the lower octane fuel in the Utah mountains, as it got vapor lock. Of course it could have been another reason, but the higher octane seemed to help on the return trip.

 

[JRRF]

With electronic timing, most modern engines will compensate for octane ratings. You may get lower fuel economy, but you won't ruin the engine.

 

[Manitoba Keith]

Actually my elevation is about 1200 feet, but our lowest octane is 87 not 85 so no problems here.

 

[obermd]

I live at 5,700 ft and use 87 octane in my 2017 Volt. At my local station this is mid-grade. 85 is available but knowing GM's small engines dislike for lower octane I'll stick with the 87.

 

[Manitoba Keith]

I live at 5,700 ft and use 87 octane in my 2017 Volt. At my local station this is mid-grade. 85 is available but knowing GM's small engines dislike for lower octane I'll stick with the 87.

Thanks. I will follow your example & use the 87 Mid-Grade. My guess is it isn't more than $0.20 a gallon more.

 

[obermd]

Thanks. I will follow your example & use the 87 Mid-Grade. My guess is it isn't more than $0.20 a gallon more.

In Colorado I've seen octane as low as 81 in the high mountain towns. Just make sure you're selecting the option based on the octane and not the "grade".

 

[alfon]

Here is the last trip using el cheapo Fred Meyer, Kroeger 87 octane gasoline (10% ethanol added) in our 2016 Volt Premier, as you can see temps are getting colder.

The gen 2 Volt engine is more efficient and less picky in my opinion of what type of gasoline grade you use.

 

[hellsop]

It's also worth thinking about that no harm comes using from using higher octane fuel than necessary, save for a small amount of money, especially if you're only VISITING places that are high enough to actually enable the use of lower fuel. Eventually you're coming back down, and you're probably not doing so on an empty tank.

 

[Cord]

Dead Sea is the world’s lowest point of land at 1,388 feet below sea level and I wonder how that works with octane.

At least the UV index is lower.

 

[jcanoe]

Dead Sea is the world’s lowest point of land at 1,388 feet below sea level and I wonder how that works with octane.

At least the UV index is lower.

The engine compression would be higher, need additional octane boost to avoid pre-detonation of the fuel in the cylinders. The engine's power output might be slightly higher. Modern engines will automatically adjust timing to reduce engine pinging so no harm.

 

[hellsop]

Dead Sea is the world’s lowest point of land at 1,388 feet below sea level and I wonder how that works with octane.

It's lower than that now. It loses about 3 feet every year, as there's still more water evaporating than falls in. I think it's about -1420 ft now, or about -433m. It'll be dry an a couple of decades unless something unusual happens.

 

[vevs]

Thoughts on octane vs altitude. Older carbureted normally aspirated engines may indeed run well on lower octane at higher altitudes for several reasons: They tend to run rich(er) at higher altitude, The realized compression ratio is reduced (less air at altitude), Both of which reduces the tendency to ping (pre detonate).