Something I noticed on westward road trip

[RamFan]

I've been back in the states for exactly a week now and have traveled quite far in these days. I returned from GTMO last tuesday and landed in Jacksonville, FL where I had my car awaiting me. I'm about half done with my summer trip, Jacksonville to Chattanooga, TN to Decatur, IL to Chicago, IL to Chamberlain, SD and today I reached West Yellowstone, MT. The rest of the trip consists of going to Seattle, WA tomorrow then returning to school in Carbondale, IL.

Anyway, the point of my little story. In SD I noticed that the regular (87) gas was more expensive than the mid-grade (89) gas, however the mid-grade gas had the 10% Ethanol sticker while the regular and premium did not. I noticed this on both the gas stations I stopped at in SD. One was a Mobil the other a Connoco. Does SD only require mid-grade gas to have ethanol blended?

Upon reaching MT today I noticed that the regular gas instead of being 87 octane, was 85.5 octane. Mid-grade was 88 instead of 89. Premium, I didn't really notice since I don't ever touch the stuff. What is up with this? I thought by law the minimums were 87,89,92?

If anyone has some insight in this I'm greatly interested.

 

[Carbon]

Ethanol is an octane rating improver. It would be harder to blend higher octane lead-free fuel without the Super Micro.

Octane requirements by engines (not referring the legal aspect) is reduced at higher altitudes.

Some Caseys in Illinois have ethanol-free 87 octane at a small premium over 89 octane no-lead with ethanol.

 

[shanneba]

It might be because the state legislature passed a 10 cent a gallon state tax on ethanol in 2010: straight gasoline has 22 cent a gallon tax rate. A 10% ethanol blend would have a lower total state tax.

http://www.state.sd.us/drr2/motorvehicle/motorfuel/index.htm
A fuel excise tax is imposed on ethyl alcohol sold by an Ethanol Producer, Supplier, Importer or Ethanol Broker. The tax imposed is $0.08 cents per gallon, plus a $0.02 cents per gallon tank inspection fee.

The octane requirements of the engine decrease with altitude, it is common for the mountain states to have lower octane fuel.

 

[Chris Meutsch]

Out in Denver the octanes are even lower.

 

[eljefino]

Less air means less cylinder pressure and detonation. Super/turbo charged engines still need the octane they need at sea level.

Lucky you found some "real gas" w/o ethanol; I'd have bought it just to make a statement.

 

[Burt]

You'll get better mpg with regular, ethanol free gas.

 

[Y_K]

Filled up in Burns, OR a week ago. Their Shell station had mid-grade with 0% ethanol, while the regular was up to 10%. Go figure.
As for high elevation adjustment, it is not that clear, e.g. my Ford/Lincoln manual explicitly advises against the adjustment, and this is on a plain vanilla modular 8

 

[RamFan]

Thanks for all the replies guys. I did not know that about the octane differentiation with higher altitude. Thanks again!

 

[Ross]

Same situation in North Dakota. Midgrade is cheapest and has 10% ethanol. The low and highgrade are more expensive and do not contain ethanol.

 

[crinkles]

Yes I grew up at 4,500 feet above sea level and I always remember as a kid going to the ocean the fuel had a higher octane down there.

 

[urchin]

85.5 RON

That is an "economy" grade of gas that would fall below regular of course. I do think there are federal regulations that would prevent that station from selling 85.5 as "regular" fuel.

I think that anything BELOW 87 RON must be labeled something OTHER than "regular".

 

[Samilcar]

Originally Posted By: Ross
Same situation in North Dakota. Midgrade is cheapest and has 10% ethanol. The low and highgrade are more expensive and do not contain ethanol.


Same in Iowa.

 

[Torino]

Yes, while working in Peru I used to run a VW over Ticlio Pass (16,000 ft. altitude). You had to keep her floored in 1st gear. John--Las Vegas.

 

[Ross]

Originally Posted By: Torino
Yes, while working in Peru I used to run a VW over Ticlio Pass (16,000 ft. altitude). You had to keep her floored in 1st gear. John--Las Vegas.


Wow, that was the theme of a 1970's move called "Sorcerer"
staring Roy Scheider.