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Guest mpls

What grade of gas to use?

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Calculate out the cost savings from using premium vs regular.  You'll find that, over the years, they are substantial. 

The cost savings of using regular 87 octane gas vs. premium 91/92 octane is about $2,500 over 400,000 miles - assuming premium costs 20 cents more per gallon and a car got 28 miles per gallon. However, there really isn't a $2,500 savings because the car running 87 octane is not going to get as good gas mileage due to deposits that will form on the intake valves and fuel injectors, reducing fuel efficiency. And the reduction in combustion efficiency means the EGR valve and catalytic converter will be exposed to a higher load of unburned hydrocarbons which will begin clogging them up sooner, which in turn reduces MPG even more. A third factor contributing to reduced MPG is that the engine running 87 will wear quicker and the compression pressure of the engine will decrease sooner. So by the time the car is getting only 25 MPG, the cost to run it is the same as when the car burns high octane gas and gets 28 MPG. Now factor in all the extra costs associated with repairing/replacing expensive fuel and emission control components and it is clear there is little money saved running 87 octane over 400,000 miles vs. running premium 91/92 octane, plus the car will be less responsive and enjoyable to drive.

 

 

I thought I'd post this because it made me laugh when I read it.

 

I don't know why people on this board can keep selling the maintenance benefits of high octane gasoline. I can understand why fuel companies do it. They do it to make more money. Check out what happened when EXXON made similar false claims about their products.

 

http://www.ftc.gov/os/1997/09/exxon.htm

 

There's only one place in their, court ordered, "Answering Questions About Octane" brochure that vaguely claims benefits and I noticed that they used, "EXXON believes", "some", "may", and "some" again in the same sentence. Wow, that's really laying down the concrete facts.

 

More general information about the pointlessness of high octane gas as it relates other fuel companies.

 

http://www.cnn.com/2000/fyi/real.life/10/18/gas.costs/

 

 

Cheers,

 

 

 

 

Regular Joe

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trap
Calculate out the cost savings from using premium vs regular.  You'll find that, over the years, they are substantial. 

The cost savings of using regular 87 octane gas vs. premium 91/92 octane is about $2,500 over 400,000 miles - assuming premium costs 20 cents more per gallon and a car got 28 miles per gallon. However, there really isn't a $2,500 savings because the car running 87 octane is not going to get as good gas mileage due to deposits that will form on the intake valves and fuel injectors, reducing fuel efficiency. And the reduction in combustion efficiency means the EGR valve and catalytic converter will be exposed to a higher load of unburned hydrocarbons which will begin clogging them up sooner, which in turn reduces MPG even more. A third factor contributing to reduced MPG is that the engine running 87 will wear quicker and the compression pressure of the engine will decrease sooner. So by the time the car is getting only 25 MPG, the cost to run it is the same as when the car burns high octane gas and gets 28 MPG. Now factor in all the extra costs associated with repairing/replacing expensive fuel and emission control components and it is clear there is little money saved running 87 octane over 400,000 miles vs. running premium 91/92 octane, plus the car will be less responsive and enjoyable to drive.

 

 

I thought I'd post this because it made me laugh when I read it.

 

I don't know why people on this board can keep selling the maintenance benefits of high octane gasoline. I can understand why fuel companies do it. They do it to make more money. Check out what happened when EXXON made similar false claims about their products.

 

http://www.ftc.gov/os/1997/09/exxon.htm

 

There's only one place in their, court ordered, "Answering Questions About Octane" brochure that vaguely claims benefits and I noticed that they used, "EXXON believes", "some", "may", and "some" again in the same sentence. Wow, that's really laying down the concrete facts.

 

More general information about the pointlessness of high octane gas as it relates other fuel companies.

 

http://www.cnn.com/2000/fyi/real.life/10/18/gas.costs/

 

 

Cheers,

 

 

 

 

Regular Joe

I also have to laugh a bit. Shell is running commercials in my market about how their gasoline gets better fuel economy than competitors, then has a little "footnote" at the bottom of the screen that says when formulated a minimum required detergency or something to that effect.

 

Well of course, if you take out as much of the detergent you legally can and the other guys haven't, you are likely to have more fuel and less "soap" (ok, not really soap, but you get the idea)

 

Let me see if I can find an online copy of some of their claims...

 

http://www.localshell.com/Content.aspx?Article=41

 

From reading it, I think they are saying the competitors fuel has minimum detergent content.

 

If they are saying 125 "free" miles over the course of 12500, that is about a 1% improvement in fuel economy. Of course, that is the "upto" figure, meaning YMMV.

 

Of course what they don't seem to address is will this be the same in all markets. We know Shell and other refiners have to formulate gasoline based on EPA requirements for a region, so what they blend for Cleveland may not allowed in Chicago or St. Louis.

 

So while what they say may be "true" I really doubt folks are going to see that 1% improvement in their mileage.

 

Besides, is a 1% change statistically significant? I know price wise, a 1% improvement in fuel economy over my 25K miles/year results in saving a whopping 4-5 gallons or less than $10 if gas is $2/gallon (It isn't here.)

 

TB

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1. 87 octane is best for cars rated at 87 octane. The higher octane ratings of premium fuels are the result of different formulations. Your mileage may go DOWN with higher octane...or it may not. We generally cannot get precise measurements - the EPA with its strict testing regimen can.

 

2. You can get fine detergents in a good gasoline. Amoco and Chevron are usually cited as good. Exxon, Gulf, and no-names are generally not.

 

3. If your spark plugs are nice and clean after a year of using a gas brand, it's good :)

 

4. As Paul would say, use Toyota brand certified gasoline (just kidding).

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Guest Paul Cherubini
I don't know why people on this board can keep selling the maintenance benefits of high octane gasoline.

Because people who have used high octane gasoline, synthetic oil and genuine Toyota parts, fluids and filters have had some incredible benefits that you cannot read about in any "educational" automotive websites on the internet. Here are two examples:

 

#1 Show me a website on the internet that educates the public about the fact that even a 1976 Toyota is capable of putting out ZERO or near zero hydrocarbon and carbon monpxide emissions after 28 years and 148,000 miles http://www.saber.net/~monarch/20rsmog.jpg There are no such websites and a huge percentage of "automotive experts" would dispute this claim or the validity of the smog test.

 

#2 Show me a website on the internet that educates the public about the fact that a Toyota engine can still have no substantial wear after 423,700 miles of being maintained with premium gas, synthetic oil and genuine Toyota parts and filters http://www.saber.net/~monarch/valveadscrew.jpg There just are no such websites and a huge percentage of "automotive experts" would dispute this claim or the validity of my picture. And they would also dispute my claim that not a single emission or fuel system componet wore out or failed or required replacment during those 423,700 miles (other than the PCV valve and oxygen sensor which are normal maintenance items).

 

Why is "insider" information like this not freely distributed to the public? Well the consequences to our economy would be catastrophic if all cars on the road were Japanese makes and lasted 600,000 miles and put out zero or near zero emissions.

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Maybe I'm confused. I thought that this thread was started to discuss "What grade of gas to use?"

 

While your comments on oil, rad fluid, and replacement parts are appreciated, they do not have any bearing on the topic.

 

Also, using the Corona as an example of why you need to run high octane fuel isn't valid. You cannot claim that your low emissions are due to high octane gas because you cannot isolate it as a single contributing factor. As I've said in the past, your emissions are most likely low due to stringent fuel requirements in your state of California.

 

As for your environmental comments, you should take some time to investigate the environmental impact from the creation of premium fuels, especially with the addition of additives. Remember, the environmental impact of fuel consumption does not start at your gas cap and end at your tailpipe.

 

Cheers,

 

 

 

 

Regular Joe

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I 've got no gripes with anyone on the board.

But as to the difference in performance in different

grades of gas.. you must ask one question:

Why would mercedes engineers prefer to

use only premium ??(of course, cost not being

a factor)

They have alot more resources for research,

than anyone on this board.

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Hey bhp02,

 

The link below (to information provided by our good friends at 76) outlines why some high end car manufacturers use high octane fuel. They design the high performance/high compression ratio engines around it. That is to say that they are designed for the fuel.

 

http://www.boyleworks.com/ta400/psp/Mythsgas1.html

 

See point #11.

 

Cheers,

 

 

 

 

Regular Joe

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the original question was whether there is

a difference in output for the internal combustion engine,

the average modern(I am assuming) including those designed

only for

and those like the 03 corolla(which will accept different Octanes)

the amount of actual energy ultimately transfered into kinetic

energy of the auto in motion for the higher grade.

And yes in my opinion, the higher octane has higher yield

and that is why mercedes prefers to design it around the premium

grades. Of course, if the mercedes engine cannot take lower grades,

we cannot compare. But my assumption why mercedes prefers

the higher grades is probably close.

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Guest 91Corolla99

fuel is like water...

 

cheap fuel causes build ups and less power to the drop

good fuel burns more efficient and the needs less to make the power

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High octane will most likely cause lower fuel mileage and reduced power sicne it effectively retards ignition timing. However, modern cars are open loops FI systems with O2 sensors, so they can alter the maps to soem degree dependign on fuel grade and a variety of environmental conditions, but the primary map is still optimized for 87 octane, 60-70 derees, low altitude and moderate huidity. They represent the mosts common dirivng siutations. Even on long trips, my mileage will typically drop by as much as 20% under 50 degrees. The engine just cant; run as super lean in those condidtions without predetination.

 

Also consider that premium gas is used less often by most drivers, therefore the tanks at the startions have a slower turn over. ON my motorcycle, if I'm in BF on a long tripE at a little hick station, I rarely get premium becasue they tend to only turn over those tanks on yearly or less basis.

 

 

What is the point?

 

There is no advantage to running high octane fuel in this type of car and most likely will cause reduced performance and mileage. Race fuel and aftermarket exhausts often have the same effect.

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the original question was whether there is

a difference in output for the internal combustion engine,

the average modern(I am assuming) including those designed

only for

and those like the 03 corolla(which will accept different Octanes)

the amount of actual energy ultimately transfered into kinetic

energy of the auto in motion for the higher grade.

And yes in my opinion, the higher octane has higher yield

and that is why mercedes prefers to design it around the premium

grades. Of course, if the mercedes engine cannot take lower grades,

we cannot compare. But my assumption why mercedes prefers

the higher grades is probably close.

Sorry, but high hoctane does not contain more energy per unit volume of fuel. The primary difference is the burn rate and stability. Higher octane fuel in more stable, ignites slower, but burn quicker. The total energy output is similar to lower octane. High octane is needed for high compression engines and those with more aggressive am profiles or advanced ignition timing. Honestly in most casrs, the diffeence between running 87 and 93 is not dramatic, but the differnece between 93 and a 107 race fuel is... as well as other additives.

 

IF I'm not mistaken, OCtane is the ratio or quantity of Octane is the fuel as compared to the other indredients of Hexane, Pentane, and Ethanol, Methanol, detergents, stabilizers, and other additives and process catalists.

 

 

I will agree that cheap gas is also bad. Typically the major brands (BP, shell, Exxon, Ctigo) sell their CIP (clean in place, fuel fro mthe next batch is run to pruge out the lines and either sold off as such or reused in a different part of the process) rinse between batches of fuel to the independents at a discounted rate. Although thsi fuel meets teh state and federal minimum rewuirements, it's of lower quality in general.

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Guest eric95tt

I'm sorry but if your run 93 octane in your corolla and think that is all there is to good performance and mileage then I have the new and improved turbo vortex mod to sell you. It's a great little fan you stick in your intake and it boosts performance by 100%! Mileage by 50%!

 

To state that there is some massive coverup because a car here and there has lasted 100's of thousands of miles running premium fuell is ludicrous. There are so many other factors that go into the performance, reliability, emissions etc of a car.My sister's 1986 sentra went over 30000 miles on its ORIGINAL oil. I guess that means we do not have to change the oil in our cars either, particularly if you own a Nissan Sentra. Wow what a breakthrough. Damn the manual! Her car is proof enough.

 

Read the damn manual. It tells you precisely what octane is required for your car, the octane it was designed for. If you want to go on believing silly myths then by all means do so.

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man, I can't believe this discussion is still going on.

This octane rating system is a ploy by the oil companies

to reap more profits from types of gas where they put

very little "extra" according to an accountant in the industry

who remains annonomous.

Why don't the oil companies use BTU's or Calories or Joules

of energy output per litre from a typical test engine for different

grades of gas ?? "Octane rating" is confusing on purpose

as I have found out that there is no strict regulation on exactly

what this means.

Also, from what I have read so far, the ethanol additives

actually decrease energy output from a gallon of gas since it has

less(mileage or power) per volume. ie you are getting ripped off

although very slightly.

 

 

We just need a corolla test vehicle on one of those machines to measure

the difference in performance with different grades of gas.

My feeling is that the oil companies put something extra in these

higher octane but it is a rip off compared to what extra you have to pay.

 

this is my last post on this topic. it is a tired horse.

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The bottom line is that the Corolla does not need and does not benefit from using high octane. If you beleve it does, then I want to see some dyno results or an objective scientific study not wishy washy cause and efect statistics. But any reputable engine tuner/builder will tell you the difference between the 2 fuels.

 

In order to get better milege, you engine needs ot make more torque through the "cruising" RPM range at low throttle positions while using the same amount of fuel. High octane gas will not do this for you. It might possibly give you a very sligth increas in proformance at hgih revs and mae the engine feel like it's running smoother (ignites later). Frankly, if you use a fuel that makes less HP, you typically will reduce engien wear and increase durability because the engine will be less stressed.

 

 

If your mileage is low and you think you NEED high octane fuel, you should try greasing your brake rotors and also check your exhaust bearign while you're at it. :P

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