Are we paying more for poorer quality gas ?

[slowrev]

The only explanation for this that I can come up with is that your engine must be retarding the timing via knock sensors when you run 89 octane. The reason I say that is because fuel energy is measured by-the-pound, and a gallon of 93 weighs less than a gallon of 89, so there is actually less BTUs to propel your Suburban down the road when you use 93 but yet you get better mileage.

No knock sensors, too primitive of a fuel injection system. Has pointless dist in it
My point is that all 93 octane gasoline should perform very close to the same, It does not.

 

[slowrev]

what's a subie?

I've never thought the price of the super was worth 1 mpg better. at sea level all our cars run fine on the cheapest gas around.

1990 subaru 4WD wagon.
I get around 4-5 MPG better mileage with the 93 octane, well the good 93 octane anyway

 

[TractorLarry]

Here's what bugs me (besides the artificially inflated prices).

I see signs now that say "May contain up to 10% Methanol".

Ok. either it does, or it doesn't. I don' think this sort of 'notification' should be allowed.

Also, what is this stuff doing to our small engine equipment?

I have NOTHING against Ethanol. I think it's going to be a big part of our future. But full disclosure should be mandated by law.

We should be the one's deciding whether we want to buy gas with Ethanol in it and pay the (effectively) higher price because it burns at a higher rate.

-Larry

 

[mjncad]

I see signs now that say "May contain up to 10% Methanol".


-Larry

I hope the "methanol" was a typo since you said "ethanol" everywhere else in the post.

As I understand it, wood alcohol is murder on fuel system components just as it is on the human body. The fuel system has to be specifically designed for wood alky.

 

[MarkFlier]

All 93 octane gas is different, there are thousands of ways to blend gas and get to a 93 pump rating. The pump rating of 93 is the average of the research and motor octane. Gas with R=101 and M=85 will have the same 93 pump rating as gas with R=97 and M=89, but the latter will perfom better. Blenders agree that the spread between R and M should never be greater than 10, but if the first blend I mentioned is cheaper than the second, that may be what you'll get. The research octane rating is important when a vehicle is under a steady load, which is why airplane fuel doesn't use the average method, only the research octane. The motor octane rating is important when the vehicle is under a heavy load like acceleration or climbing hills. That's why the second blend I mentioned above is better, and that's probably why you can tell the difference. If you're buying from a branded station, the gas will probably be consistent (bad or good) because those stations usually enter into supply contracts with the jobber and will usually get the same supply source. Unbranded stations don't always use the same jobber, so there could be some inconsistencies at that one station. Most unbranded fuel stations use gas that comes from one of the majors (without the additives that are exclusive to the brand), but you could be getting Exxon gas one week and Phillips the next. I prefer branded stations because I believe there will be consistency, but when I worked for an independent blender, I had more confidence in our gas than any other. Your SUV probably doesn't need 93 pump rating. Most 89 pump rated gasolines will have a research rating of about 93 to 95. A lot of owners' manuals confuse people by referring to the research octane rating requirements, when you have no way of knowing what that is for your fuel.

 

[MarkFlier]

Here's what bugs me (besides the artificially inflated prices).

I see signs now that say "May contain up to 10% Methanol".

Ok. either it does, or it doesn't. I don' think this sort of 'notification' should be allowed.

Also, what is this stuff doing to our small engine equipment?

I have NOTHING against Ethanol. I think it's going to be a big part of our future. But full disclosure should be mandated by law.

We should be the one's deciding whether we want to buy gas with Ethanol in it and pay the (effectively) higher price because it burns at a higher rate.

-Larry

These stations may be getting their fuel from different blenders, some of whom still use MTBE and some of whom use ethanol. MTBE is better because it is only soluble in water at 400 parts per million, where ethanol is 100% soluble. This means that if you went to a gas station that had MTBE in one tank, ethanol in another, you could pour fifty gallons of water in each and stir them, and all the ethanol would combine with the water and settle to the bottom. Only a small amount of the MTBE would combine with the water and settle to the bottom. This is why MTBE was the oxygenate of choice for years, because there is water in tanks and pipelines that would pull out ethanol or methanol and affect the blend.

 

[cp1969]

What altitude are you operating at?

You'd only need the higher octane <1,000 feet above sealevel.

For each 1000 feet of altitude the atmospheric pressure will drop by a little less than 1 inHg thereby decreasing compression and allowing your engine, at altitude, to operate better on lower octane fuel. The higher you go, the less octane you need.

Mr. Pup, that doesn't hold true for supercharged or turbocharged engines, does it?

 

[MadReferee]

...Most unbranded fuel stations use gas that comes from one of the majors (without the additives that are exclusive to the brand), but you could be getting Exxon gas one week and Phillips the next.

You don't state in your profile where you are located (shame on you) but in the New England area, ALL fuel, except for Mobil which has its own bulk storage facilities, comes frome the same bulk storage tank. The only difference between the brands (branded and unbranded) is the additive package.

Also, I have never seen any pump that did not use the (R+M)/2 method for determining the octane rating. I believe that federal regulations require the method used to calculate octane be clearly visible on the pump.

 

[jayhaitch]

MarkFlier: that makes sense. I bought an 86 Porsche 911 2 years ago, Euro-spec, imported from Japan of all places to Canada by a boutique German used car dealer in Vancouver. The sticker inside the filler door said use RON 98 only. This is the high compression no catalyst version of the 3.2 litre boxer. The highest premium AKI here is 94, but it's an ethanol blend. I'm all for ethanol, but not in an old classic car. The highest pure premium was AKI 92. They've now dropped them all to 91, at the same time. Fuel prob comes from the same supplier then, no?

Anyway, I emailed Shell as some of their stations have dedicated premium hoses so I've been using Shell exclusively in the Porsche. Their reply was 92 AKI is 98 RON. They didn't say what the MON was however, so I'm not sure if it really is 98 RON, or is it just their way of saying "That's all we got buddy boy." The car runs well though, no knock, so I guess they're correct. Why did they drop it to 91 at the same price? Oh yah, profit.

 

[mjarrels]

I heard on the radio today that the new blended fuel is creating major issues in vented marine engines and fuel tanks.

mark