Fuel Octane - What's the Dealio?

[mariohere]

I'm trying to understand what's happening with my car when I change the octane of the fuel that I'm using. When I use a low grade octane such as 89 I get about 28mpg. When I use High Test such as 93 octone I get about 32 mpg. What does this mean?

When I used to drive air cooled VW's I used the High test to reduce the pinging and reduce the engine temperature.

When I used to race motorcycles I used the high test and the engine put out more power.

It seams to be congruent then that the high test would result in better fuel mileage for my corolla - a 1999 LE. More efficiency better mileage.

But everything I find on line says that using the higher octane fuel will Not produce better fuel mileage. Why is my experience contrary to what everyone else says on the internet? I have new spark plugs in my car and it has 96,000 miles on it. Barely broken in.

Any feedback would be appreciated as my girlfriend is doubting my sanity.

 

[Scott O'Kashan]

A public service notice from the Federal Trade Commission -

http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut12.shtm

Facts for Consumers

The Low-Down on High Octane Gasoline

Quote:
Are you tempted to buy a high octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner's manual.

The only time you might need to switch to a higher octane level is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars.

Unless your engine is knocking, buying higher octane gasoline is a waste of money, too. Premium gas costs 15 to 20 cents per gallon more than regular. That can add up to $100 or more a year in extra costs. Studies indicate that altogether, drivers may be spending hundreds of millions of dollars each year for higher octane gas than they need.

 

[HeavyD]

Think of 'octane' in the terms of stability. The higher the # of octane, the more stable it is. Low octane fuel has a tendancy for early detonation. Higher octane fuels offer a more stable platform for your vehicle to work off of. You get more of an efficient burn on higher octane fuel than you would on lower octane fuels. The misnomer is that higher octane fuel is a cleaner fuel. Not true, it's just refined differently in order for it to reach the higher stability it has.

 

[05corolla]

I use 87 in mine and E-85 in the stang

 

[mariohere]

Octane

you should try 90 octane in the corolla. You will likely get 4 mpg better. but you need to run a couple of tankfuls through to see the results. It will more then make up for the extra cost of the 90 octane. I didn't notice much difference between 90 and 93. Seams like 90 is the way to go.

I use 87 in mine and E-85 in the stang

 

[Scott O'Kashan]

you should try 90 octane in the corolla. You will likely get 4 mpg better. but you need to run a couple of tankfuls through to see the results. It will more then make up for the extra cost of the 90 octane. I didn't notice much difference between 90 and 93. Seams like 90 is the way to go.

The Federal Trade Commission has stated that there are not any fuel economy benefits with higher octane fuels. It's a waste of money.

 

[mariohere]

Octane ratings

I notice about a 4 mpg difference in the winter months, probably because the fuel is different, between the 87 octane and the 90 octane.(in some parts of the country the gasoline used in the winter is different then the gasoline used in the summer) The difference is less during the summer months. It doesn't much matter what the Federal Trade Commission says - the proof is in the pudding for anyone who wants to try it. I've been measuring mine for about a year now. There are some really good apps for the Samsung Galaxy tab out there such as Fuel Calculator by appjigger studios.

The Federal Trade Commission has stated that there are not any fuel economy benefits with higher octane fuels. It's a waste of money.

 

[Scott O'Kashan]

http://www.ftc.gov/bcp/edu/pubs/cons...tos/aut12.shtm

Facts for Consumers

The Low-Down on High Octane Gasoline

Quote:
Quote:
Are you tempted to buy a high octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner's manual.

The only time you might need to switch to a higher octane level is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars.

Unless your engine is knocking, buying higher octane gasoline is a waste of money, too. Premium gas costs 15 to 20 cents per gallon more than regular. That can add up to $100 or more a year in extra costs. Studies indicate that altogether, drivers may be spending hundreds of millions of dollars each year for higher octane gas than they need.

 

[HeavyD]

@ Mariohere. Yeah, most vehicles DO get better mileage during the winter. Cold fuel burns better too, regardless of the octane rating. Basically the same concept as NO2. All NO2 does is DRASTICALLY reduce the temperature of the incoming fuel to the combustion chambers. But NO2 drops it WAY below the average 20-30 degrees we get in the winters.

 

[goku]

Corolla is designed for 87 octane fuel. However, if the car is older and has carbon deposits, higher octane fuel may prevent pre-ignition and certainly will reduce tendency of detonation if it's predisposed to it due to the age. If your car runs better on higher octane, use it. I don't recommend blanket statements like 'always use 87 or always use premium'. I say, always use what works best and generally what gets the best fuel economy is what's best for the car because that means it's running optimally and the computer doesn't have to retard timing.