Benefits of High Octane at High Altitude?

[rideandslide]

Get a grip.



You could learn a few things still. You might start with the following article:

http://www.argusleader.com/article/20120624/NEWS/306240015/85-octane-gas-risky-cars

Yeah I guess you didn't read the follow-up to this situation. South Dakota's government in March passed law that allowed 85 octane to be sold in the 9 Western counties, which happen to be high elevation. The bigger issue in SD was the gas wasn't labeled, and nobody disputes 85 Octane being used at 1500 ft zones such as the eastern half of SD. Last repsonse to you on the subject.

 

[MikeM.]

Yeah I guess you didn't read the follow-up to this situation.

I guess you did't read this part:

“Manufacturers say that drivers have to comply with the terms of the warranty, and the warranties say that you need to use 87-octane, period,” said Dan Gage, spokesman for the Alliance of Automobile Manufacturers, a trade group that represents 12 large automakers. “Eighty-five (octane) should not be used under any conditions.”

What part of "Eighty-five (octane) should not be used under any conditions” do you not understand?

Also this:

Volkswagen engines aren’t tested on anything lower than 87-octane, Schmidt said. To meet federal emissions and fuel economy standards, the industry is moving toward smaller, more efficient engines with turbocharged, direct-injection systems, said Stuart Johnson, a manager at Volkswagen who focuses on regulatory issues.
“From an industry perspective, (South Dakota’s proposal) is a step in the wrong direction,” he said. “If anything, in the future, we’re asking for more octane.”
Enforcing warranty terms in cases of engine damage that was caused by low-quality fuel would be difficult but not impossible, experts say.
This damage could emerge only after years of use, and a typical factory warranty might have expired by that time, Gage said. He declined to comment more specifically on how warranty voidings could be determined based on fuel use, saying it would depend on the manufacturer.
“How would they later prove that? I suspect they would have to build a case,” he said.
Calls to several local dealerships to discuss the warranty implications of using low-octane fuel were not returned.


Using low octane at high altitudes made more sense before cars had barometric sensors. The problem is, the car knows that the barometric pressure is lower so it advances the timing. But it has no way of knowing that you filled the tank with fuel below the minimum expected octane until it senses detonation and, as the article pointed out, the detonation sensor is an emergency measure only and shouldn't be relied upon for normal running. After detonation happens the engine management must dial back the timing and performance suffers compared to fuel that meets minimum standards.

Modern cars are very different from gramps '56 Chevy.

 

[Bladecutter]

Cars that have turbochargers that run on gasoline tend to have high octane fuel requirements, not 87 octane fuel requirements.
If you're running a car with a turbocharger on anything less than premium, you're an idiot.

Your article is also a discussion about 85 octane fuel being sold in low altitude areas, at gas stations that are not concerned at all with the quality of the fuel being sold to their customers.
No one should use 85 octane in low altitude regions, like I said before.

Cars that are designed to run on 87 octane fuel are 100% fine running on 85 octane fuel here in Colorado, as I said before.

Like I said before, there are MILLIONS of cars, motorcycles, and trucks here, and have been for DECADES, and there are MILLIONS of car, motorcycle and truck owners using 85 octane in their vehicles, INCLUDING VW's, and they are not blowing up. If there was ANY amount of risk, there would be THOUSANDS of destroyed engines every single year, and YOU, ME, and EVERYONE ELSE on the planet would KNOW about it. Millions of cars, trucks, and motorcycles putting hundreds of thousands of miles on them up here in high altitude over their lifetimes, and they are not having piston failure, cylinder head gasket failure, valve face and seat failure, nor any other failure that would be associated with pre-ignition from running too low of an octane fuel for long term.

Every single vehicle manufacturer is represented in this real world sample.
Every single one of their products is represented in this real world sample.

Can you explain that?

BC.

 

[MikeM.]

Your article is also a discussion about 85 octane fuel being sold in low altitude areas, at gas stations that are not concerned at all with the quality of the fuel being sold to their customers.

Actually, the quote from the Automobile manufacturers Trade Association said 85 octane should not be used under ANY conditions. He did not limit it to low altitude areas.

Cars that are designed to run on 87 octane fuel are 100% fine running on 85 octane fuel here in Colorado, as I said before.

Yes, that's often true. But I wouldn't recommend it on cars with barometric pressure sensors because they are designed to advance the timing at higher altitudes. This can cause detonation (at least until engine management realizes there is detonation and dials the timing back).

Millions of cars, trucks, and motorcycles putting hundreds of thousands of miles on them up here in high altitude over their lifetimes, and they are not having piston failure, cylinder head gasket failure, valve face and seat failure, nor any other failure that would be associated with pre-ignition from running too low of an octane fuel for long term.

Making a wild, all-encompassing claim, with not a shred of supporting evidence, does not make it true, even if you repeat the same claim multiple times. The fact is that numerous cars blow head gaskets, over-heat at the side of the road, throw rods and melt pistons. It happens every day. How many of these are due to sub-standard fuel is not well documented but, you can bet it's a few (and I don't want to be one of them).

 

[CX-SV]

Thanks BC.

Since I open this thread I decided to experiment myself using 91. I typically get an average of 28.2mpg with 85. On 91 I'm getting 29.3mpg so far and only two fuel-ups. Please note I drive up and down the foothills everyday (live up, work down). I will update the numbers here after the next one.

Any updates (hopefully you are not sorry you asked)? Best bet in CO would be a mid-grade gasoline, that would be cheaper and meet the minimum octane requirement per Mazda for CX-5.

 

[125558]

Ok, back into this. Sorry it took me so long to report back; been very busy with work.

After several fuel-ups (about 8 or 10) with 91 octane gas at altitude my average gas millage went from 28.2 to 29.6; not a big increase but at least is something. I can't really measure if there was any improvement in HP or performance (I'm not a scientist or mechanics engineer) but IMO it feels a little bit more responsive specially going uphill.

Having said this I will stick to 91, IMO (again) it does add some benefit using 91 octane vs 85. Price per mile will probably still defeat the increased millage I got, but at least I know my engine is running cleaner. Besides, going from $3.29 to $3.49 a gallon (in my area) is only abut $2.4 more per fuel-up; I don't think is a big deal.

 

[CX-SV]

Ok, back into this. Sorry it took me so long to report back; been very busy with work.

After several fuel-ups (about 8 or 10) with 91 octane gas at altitude my average gas millage went from 28.2 to 29.6; not a big increase but at least is something. I can't really measure if there was any improvement in HP or performance (I'm not a scientist or mechanics engineer) but IMO it feels a little bit more responsive specially going uphill.

Having said this I will stick to 91, IMO (again) it does add some benefit using 91 octane vs 85. Price per mile will probably still defeat the increased millage I got, but at least I know my engine is running cleaner. Besides, going from $3.29 to $3.49 a gallon (in my area) is only abut $2.4 more per fuel-up; I don't think is a big deal.

How about my question above regarding "mid-grade gasoline, that would be cheaper and meet the minimum octane requirement per Mazda for CX-5.",

Or in other words, why not use the correct grade of gasoline?

Is mid-grade / 89 octane gasoline available at gas stations in CO?

 

[piotrek91]

Yes, that's often true. But I wouldn't recommend it on cars with barometric pressure sensors because they are designed to advance the timing at higher altitudes. This can cause detonation (at least until engine management realizes there is detonation and dials the timing back).

hmmm.. if what you are saying about cars advancing timing based on the barometric pressure sensors applies to the CX-5, than it should be possible to advance the timing at sea level by tinkering with the barometric pressure sensor.
If I understand things correctly advanced timing, as long as there is no knock generally corresponds to an increase in power. Knock could be prevented by running 91 octane.

Of course this is all just speculation and most likely the small increase in power would not be worth the risk of breaking something.

 

[125558]

How about my question above regarding "mid-grade gasoline, that would be cheaper and meet the minimum octane requirement per Mazda for CX-5.",

Or in other words, why not use the correct grade of gasoline?

Is mid-grade / 89 octane gasoline available at gas stations in CO?

85 octane meets the minimum requirement but only int he states at higher elevations, like Colorado. Mid-grade here is 87. Gas ratings up here are as follows:

Regular: 85 (87 @ sea level)

Mid-grade: 87 (89 @ sea level)

Premium: 91 (93 @ sea level)

 

[CX-SV]

85 octane meets the minimum requirement but only int he states at higher elevations, like Colorado. Mid-grade here is 87. Gas ratings up here are as follows:

Regular: 85 (87 @ sea level)

Mid-grade: 87 (89 @ sea level)

Premium: 91 (93 @ sea level)

Note: Mazda specifies the following.


Your Mazda will perform best with fuel listed in the table.
Fuel Octane Rating* (Anti-knock index)
Regular unleaded fuel 87 [ (R M)/2 method] or above (91 RON or above)
* U.S. federal law requires that octane ratings be posted on gasoline station pumps.
Fuel with a rating lower than 87 octane (91 RON) could cause the emission control system
to lose effectiveness. It could also cause engine knocking and serious engine damage.


Thanks, therefore answer to my question above is mid-grade/87 octane is offered in CO.

 

[sylva143]

As you may know from my earlier posts, I use 93 octane here in the North Carolina mountains, with driving altitude between 2,500 and 6,700 feet. After some experiments and some suggestions by experts (edmunds.com), I'm comfortable paying about $3.00 per tank to get the good stuff. I mostly use Shell VTech, so I know I'm getting dependable gas that will keep my engine clean, and there MAY be some additional benefits.

We really aren't talking about that much money. What is the difference between 85 and 87 octane in cost? Maybe .15 cents per gallon? Is it really worth taking a chance for such a minor amount of cash? There seems to be something different about gasoline in the USA that we don't see with other products. Everyone seems to focus on saving a very minor amount of money, sometimes burning precious fuel by driving all over town to save a few pennies per gallon. It seems crazy to me. There is little focus on the product quality or how it might impact the automobile, hence all of this hand wringing about upgrading to 87 octane in high altitude states.

I have a better solution...start making the coffee at home, and skip Starbucks. You'll save a lot more money than worrying about the price of gas.

 

[ryan.andersen91]

It's been said time and time again by professionals that 85 is the equivalent to 87 in higher elevations (due to thinner air causing lower compression). I've been told by my techs it won't void my warranty. I'm going to keep using it. There is no reason for me to pay more so I'm not going to.

 

[CX-SV]

We really aren't talking about that much money. What is the difference between 85 and 87 octane in cost? Maybe .15 cents per gallon? I have a better solution...start making the coffee at home, and skip Starbucks. You'll save a lot more money than worrying about the price of gas.

Yes, my preference is to make PEET's House Blend at home with Cuisinart machine, much better than that crap served at STARBUCKs, lol, not to mention cost savings.

Gas is cheap in the US, but that's offtopic.

That's why I asked the question (a couple of times), and later found out the correct grade (87) of gasoline is actually available in CO.

 

[MikeM.]

It's been said time and time again by professionals that 85 is the equivalent to 87 in higher elevations (due to thinner air causing lower compression). I've been told by my techs it won't void my warranty. I'm going to keep using it. There is no reason for me to pay more so I'm not going to.

What are you going to do with the huge pile of money you're going to save by running below spec fuel?

 

[ryan.andersen91]

What are you going to do with the huge pile of money you're going to save by running below spec fuel?

It's the little things. Save money where you can.

 

[125558]

Note: Mazda specifies the following.


Your Mazda will perform best with fuel listed in the table.
Fuel Octane Rating* (Anti-knock index)
Regular unleaded fuel 87 [ (R M)/2 method] or above (91 RON or above)
* U.S. federal law requires that octane ratings be posted on gasoline station pumps.
Fuel with a rating lower than 87 octane (91 RON) could cause the emission control system
to lose effectiveness. It could also cause engine knocking and serious engine damage.


Thanks, therefore answer to my question above is mid-grade/87 octane is offered in CO.

Mazda recommends Regular fuel not mid-grade. At sea-level regular is 87, for us is 85. I asked my mazda dealer about that when I bought my car and they told me 85 was totally fine to use up here.

What happens is at higher altitude the atmospheric pressure is lower and oxygen amount is lower too; so fuel will not burn completely as it would at sea level; allowing us to use lower octane fuel (save some $) and get the same results.

 

[125558]

It's been said time and time again by professionals that 85 is the equivalent to 87 in higher elevations (due to thinner air causing lower compression). I've been told by my techs it won't void my warranty. I'm going to keep using it. There is no reason for me to pay more so I'm not going to.

Thank you, exactly right!

85 here is 87 downhill.

 

[V8toilet]

$2 a day = $728 a year saved less whatever it costs you to brew your own. If you drive 15,000 miles a year and average 30 MPG than .15 cents a gallon more will cost you $75 a year more or 37.5 cups of $2 coffee's. I've run 87 and 93 octane back to back and noted no change in mileage and no increase in 0-60 using my G-tech accelerometer.

 

[MikeM.]

What happens is at higher altitude the atmospheric pressure is lower and oxygen amount is lower too; so fuel will not burn completely as it would at sea level; allowing us to use lower octane fuel (save some $) and get the same results.

Not true.

The engines ECU monitors the ambient air pressure. It knows when the engine is at altitude and adjusts the fuel mixture as well as the ignition timing map to suit the air that is less dense. But the compensation tables assume you are running fuel within spec. This wouldn't be the first time a dealership employee gave less than good advice.

Always run the minimum (or higher) octane recommended by the manufacturer and leave the 85 octane gas for the old school cars without barometric pressure sensors.

 

[dergibog]

Get bent Mike. My dealer in Lakewood Co said 85 was OK too.