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Weird Gas / Mpg Question!


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Good Morning!

I have a really weird question concerning gasoline and mpg. I know this topic has been beaten like the Eagles on Monday evenings, but here I go!!! I have been reading about some members here using premium fuel instead of regular 87 octane. Well, I coughed up the extra money and went to the Mobil Gas Station and filled up with 93. I drove 330 miles and no difference. In fact, I needed 14 gallons to fill it up. My last one I made 360 miles on 12.5 gallons and that was using 87 octane?!?! Is this weird or what? Can anyone comment on this or am I just crazy?

Brian

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Yes, this has been an ongoing battle between the members, whether to use Premium or Regular fuels. I have owned 3 ES's since 1991 and I constantly kept switching octanes on all these cars, looking for increased performance and/or gas mileage, and to this day I haven't found any differences, except in my wallet.

If I found ANY differences, or if the engine didn't run as well, I would switch back to Premium.........but as of now I'm sticking to Regular fuel.

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OK . . . believe it or not, but if your car is not designed to be used with Premium gasoline, then PREMIUM WILL NOT INCREASE PERFORMANCE OR DECERASE ENGINE WEAR. The stupid (or I guess you could agrue smart?) big oil companies want you to believe it will, because they make more money off of it. They even use sly marketing tactics such as labelling "bronze", "silver", and "gold" to make you think that the "bronze" gasoline is inferior to the "gold".

One must understand the difference between the gasoline grades to understand why premium does nothing for a car that does not require it.

Basically, premium gas is more difficult to ignite than regular gas. The point of premium gas is to prevent engine knock in higher-performance engines. For example, if you put regular gas in a premium gas requiring car, the more flammable gas can ignite when you don't want it to (misfire). I know that my '92 ES300 requires only regular gas, so I assume that your '94 only requires regular as well. Because it only requires regular, this means that the will not misfire with regular gas. This also means that the engine will not misfire with premium gas either, but it will also not burn properly as your car is not designed for it. And actually, by putting premium gas in a non-requiring car, you can be doing more harm than good and DECREASING your fuel economy. Yes, that's right, PREMIUM fuel can HARM your car! It makes sense. If the gas is more difficult to ignite, then this can lead to carbon deposits and engine clogging and other negative effects such as increased emmissions.

Didn't you ever notice how the gas companies never have any informative publications/brochures explaining the real differences between gasoline grades? It's because they don't want you to know. They want to make more and more money by feeding off of innocent people's ignorance a desire to keep their pride-and-joy cars in tip top shape.

As a rule of thumb, it is pretty simple: use the grade of gasoline that is indicated in your car's user manual. The manfacture made the car, so they know what works best with it.

Regards,

Bryan

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The only time that I noticed a difference was with my 96 infiniti I30, when I used regular grade. from time to time the oxygen sensor indicator would come on and one dealer exlained that I should throw in a tank of premium and that will eliminate the problem. He suggested stay with regular as common practice unless the light comes on. Whether it was true or not, I perceived that the car performed a little better with higher octane, especially on highway.

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My 01 owners manual says the same thing you mentioned brian. However I ave noticed quite a bit of difference when using Sunoco ultra 94 compared to regular Sunoco 87 fuel. The idle is not as smooth (smooth enough mind you) when I use the regular gas & the acceleration isn't instant either.....a slight hesitation. I personally notice I get more per tankful with the 94 over the 87 (about 75 - 100 kms more). My rule of thumb is when gas prices are dirt cheap by today's standards anyways (we have an ongoing fight here in the Toronto area where by the big 4 gas companies are trying to put the independents out of business with 65.5 cents a litre gas the last couple weeks) I can get the 94 for the price of regular when it's at it's highest (around the 80 cent mark or there abouts) so I figure why not put the premium stuff in.......if regular is really high & I have no choice but to get gas, I will use the regular.

:cheers:

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Hmm . . . weird that you notice an improvement. Are you sure that it is not because of a slight change in driving style (for fuel economy)? Maybe you did more highway driving for that tank? but then, you said you noticed an improvement in idle and acceleration too . . . hmmm. Theory says it shouldn't improve . . .

I wish has prices were as cheap in Guelph as they are in Toronto! Why should you guys only have to pay 65.5 when we have to pay 79.0 only 80 kms away?! It's just not fair :(

Regards,

Bryan

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My manual also says 91 octane. I drove it w/ 87 octane for awhile, and it doesn't idle/run as good.

I put 93 octane in and it runs much better, has greater fuel economy by 1-2mpg on a long trip, and has a noticabl amount of more power. I think it is car dependent. The 1997+ es300's have differently designed engines than pre97. They could be designed to take advantage of the higher octane.

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Yes, it is all in the design of the engine. If it requires premium, then premium is what it should get or you may have engine knocking and will put extra wear and tear on your engine. If your car does not require premium (such as my '92), then regular is what it should get.

Pretty simple :)

Regards,

Bryan

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I run 87 in my 98 without any issues. I have tried 89 and 93 at Mobil and nothing changes. No better MPG, no better running, nothing.

My inlaws our a garage and also sell gas and they even stated just buy the cheaper stuff and maybe once per year put some injector cleaner in.

So far after 35K mile I get from 23.5 to 25.2 in city with ac on and works fine.

Now my GSX-R1100 is the opposite.

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I drive a daily commuter in the Acura EL, which is essentially an Acura wrapped with the Civic Si's engine. I find that if I fuel it up with 87 gas, the engine feels a little rougher and it is a little bit noisier, which is suspected because of the extra pinging in the pistons. But powerwise and mileage, there isn't really that much of a difference.

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:cries:

Here's the thing, my MPG went down! I thought that if you use a higher octane fuel, that the engine would not have to work as hard, and thus, use LESS fuel and your MPG goes up! Isn't that how it is supposed to work? I am confused :unsure: Anyhoo, the owner's manual suggests 91 octane which is a middle grade, right? What possible good is it to use a fuel that is ONLY alittle better than 87? What would happen if I bought an additive that boosts octane to 104? I wonder what would happen? Or, if I went to Sunoco and filled up with 94? Anyone know what Shell's new gasoline rating is = "V-Power"? What does that mean and what is it's fuel rating?

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maybe its your driving style?

or maybe it is the gas you buy?

but i think there is a difference..but im still trying to figure it out myself

recently ive been putting in generic regular/87 octane gas

and yesterday i actually noticed my engine felt a little rougher than before, when i switched back and forth from the different grades of generic gas.

and i have a question

if it use just the regular gas making it rougher..then i should have no major problems?

but what else could cause engine to run rougher?

i last changed my oil about 1000miles ago, and the other fluids is fine and no check engine light is on.

-mike

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Ok to straighten out a few misconceptions

you will not lose power or mpg by uising a higher ocatance ,as you drive a car goverened by a computer and fuel injection not a carburator

this means the ecu will change the timing to adjust for lower and higher octance, meaning if you have used cheap gas for its whole life you will now have higher burn temps which will be clearing out the carbon build up but it is not instant either. it will take a few tanks to notice a difference in a car with large deposits, this will also lower your inital data recoreded from changes in fuel usuage as the carbon create hot spots with the higher temp which will cause a slight timing retardation until it is retified by it blowing the carbon out to a poiint, which is hard unless you get a motorvac to thoroughly remove it.,

I have air fuel ratio meters in both my cars as well as a pyro which monitors the burn temp precisley,by reading this it shows me th temps rise much better with 94 ocatne as well as much better than any crap gas shell sold me for 5 years before i switched for the better.

So all in all if you can get 600++km a tank consistanly like mine with 1000lbs added with modifications and stereo dragging around on top of it with chrome 18's then make an argument that 87 is better but everything i have learned and seen in my personal test come back with positive results every time i fill up my tank.

using a higher octane allows your ecu to make a descion on how much to !Removed! or advance the timing according to the needs of the driver not its limitations of knocking which will never be felt by a driver since the knock sensors are way to sensative and respond faster than you can think you heard a knock.

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I do notice a difference & will continue to get Sunoco 94 as long as it's "reasonable" in price. My buddy has a 02 Camry V6 LE & he fills up with 94 only about once a month & the rest of the month he uses Sunoco 87 (don't forget that Sunoco uses up to 10% Ethanol in their fuel which burns better & has less sulphur content PPM which is better for your car's performance & it's emissions control devices) without any signs of decreased performance. B)

bdonk, I agree with you that the prices shouldn't be so high out in the Guelph area, but Toronto is the largest market in Canada so they have many independent stations that they are trying (the big 4) to knock out of business. That lasted only about two and a half weeks.......things seem to be back to "normal" now however since the price of oil is at new record prices at $45 a barrel! :blink: :cries: $.78.9 at several Sunoco stations this morning.

:cheers:

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funny thing is how has a barrel price gone so similar to the 80's oil shortage but the refined price is double of what it was then if you don;t skew the data with a recalculation for inflation????

Somehow we get gouged nicely, technology makes things easier and cheaper to do, if not then why the hell don;t they make it like they used to make it.

I noticed a few months ago it was 10-15 cents more in guelph when i was down there for a day ,i was so suprised.

and there is a difference in performance in the ocatane levels using the seat of your pants dyno is not accurate.

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funny thing is how has a barrel price gone so similar to the 80's oil shortage but the refined price is double of what it was then if you don;t skew the data with a recalculation for inflation????

Somehow we get gouged nicely, technology makes things easier and cheaper to do, if not then why the hell don;t they make it like they used to make it.

I noticed a few months ago it was 10-15 cents more in guelph when i was down there for a day ,i was so suprised.

and there is a difference in performance in the ocatane levels using the seat of your pants dyno is not accurate.

I think you might be surprised about the effects of technology. You've grossly oversimplified a number of factors.

1. Environmental costs have skyrocketed since the 1980s. You pay for that at the pump. In addition, more expensive oil extraction methods are now required as some of the easiest oil has been depleted (particularly in the US)

2. Crude oil prices have dropped by about 50% since 1980 in constant dollar (inflation adjusted) terms (http://www.latimes.com/business/la-fi-oil4aug04,0,596551.story?coll=la-headlines-business).

3. Gasoline prices have dropped by about 50% since 1980 in constant dollar (inflation adjusted) terms (http://www.chartoftheday.com/20030827.gif).

That's better than one would expect in a situation where you have a high and increasing fixed cost. No one's gouging anyone.

As for the seat of your pants being more reliable than a dynanometer, I can only laugh. Anyone who really believes that the seat of the pants is more accurate than a dyno is only fooling himself.

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I have a similar problem with brian. In my 96 ES300's manual says to use 87 as MINIMUM, but 91 is recomennded for better performance. When i first bought it the ES I used 87, and i got VERY good gas mileage. But recently my check engine went on, and i took it to the dealers and he said simply to put 91 in it from now on, which i did, the problem is that i have notice a performance increase, BUT my MPG has gone way down. The car is way more responsive now with the 91, but my MPG's went too far down and its cutting deep into my pockets, So i dont know if i should switch back to 87. wat to do?

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