What type of octane I should use???

[swng]

Point understood friend!

[why?]

If it actually does anything to them. The person who wrote the website stated that he has soaked hoses and other parts in up to a 20% acetone/ 80% gasoline solution for months, and has seen no adverse affect except in the highest concentration he used to test that theory. Considering 3 ounces to 10 gallons is a .002 % concentration.

[AutoTech1]

Originally Posted by why?

If it actually does anything to them. The person who wrote the website stated that he has soaked hoses and other parts in up to a 20% acetone/ 80% gasoline solution for months, and has seen no adverse affect except in the highest concentration he used to test that theory. Considering 3 ounces to 10 gallons is a .002 % concentration.

Yeah true... You do make a good point.

[DollaZo]

sup all

just letting you all know that when I first got my Yaris 1.5L i thought that if I had put expensive fuel in the car that it would benefit my car. 91 octane being cheaper than 98 which is what I put for about 3 months. After a while I started to notice that the car was being harder to drive in terms of playing with the accelerator and the clutch. After speaking to a family friend he recomended me to start using 91 octane. Instantly I noticed that the car was easier to drive, it felt as if the car was happier to drink 91 than 98. So in my opinion I would not recomend using 98 octane as the car was made to run with 91.

[SophieSleeps]

Originally Posted by DollaZo

sup all

just letting you all know that when I first got my Yaris 1.5L i thought that if I had put expensive fuel in the car that it would benefit my car. 91 octane being cheaper than 98 which is what I put for about 3 months. After a while I started to notice that the car was being harder to drive in terms of playing with the accelerator and the clutch. After speaking to a family friend he recomended me to start using 91 octane. Instantly I noticed that the car was easier to drive, it felt as if the car was happier to drink 91 than 98. So in my opinion I would not recomend using 98 octane as the car was made to run with 91.

Yeah. that makes no sense.

Octane is a rating of how resistant the car is to detonation.
running higher octane will have no effect on the car.
The stock ECU will not continue to advance timing blindly if you put in higher octane fuel.

If it is tuned for a 91 octane, you should use no less than 91. However, any more than 91 octane will not make any difference unless you have some serious engine mods and have pushed tuning to a different threshold for knock.

It's funny to see what people say about Octane.
I always hear people talking about how their car runs better on higher octane, or how some people occasionally fill up on higher octane to clean the fuel system or whatever. I laugh silently becuase it takes too long to explain to them that they are clueless.

It's also like when people put on an intake and they say "I can definatley feel a difference. the car is much more powerful"

[fearturtle44]

It is amazing that people still believe running a higher octane does something tremendous for their engines. It does nothing. You might as well spend the extra $$$ on lottery tickets.

Kevin

[SophieSleeps]

Originally Posted by fearturtle44

It is amazing that people still believe running a higher octane does something tremendous for their engines. It does nothing. You might as well spend the extra $$$ on lottery tickets.

Kevin

Thank god someone else on this forum makes sense.
Maybe someday people will learn.
I'm liking the lottery tickets idea.

[why?]

Actually, that is not true.

1. Gas companies put their best additives only in the highest octane gas, so it can have a cleaning out type of effect.

2. Car companies do all their testing on a car using the highest octane available, especially the gas mileage test. Their must be a reason.

3. It has been noted that higher octane fuel will give better mpg results, however, at this moment the cost of the higher priced fuel outweighs the mpg gains of the better fuel.

4. Running octane lower than recommended will usually destroy a vehicle pretty quickly. Gee, I wonder why.

[SophieSleeps]

Originally Posted by why?

Actually, that is not true.

1. Gas companies put their best additives only in the highest octane gas, so it can have a cleaning out type of effect.

2. Car companies do all their testing on a car using the highest octane available, especially the gas mileage test. Their must be a reason.

3. It has been noted that higher octane fuel will give better mpg results, however, at this moment the cost of the higher priced fuel outweighs the mpg gains of the better fuel.

4. Running octane lower than recommended will usually destroy a vehicle pretty quickly. Gee, I wonder why.

You've been listening to too many people who have been perpetuating rumors.

1. Which additives do they put in? What do they do? I think it sounds like you are reaching on your comment. What is the "best additive"?

2. Car companies may test cars with high octane gas, but only to create a tune that is safe. Once it is safe, they run it at the recommended octane. This is standard. It would be dumb to run it the other way around.

3. It has been noted by stupid people that higher octane gives better mileage. What is the reasoning behind this?

4. Running lower octane gas than recommended can definately do damage to a vehicle. It's because the vehicle is experiencing detonation or pre-ignition due to the octane being too low for the tune.

When you say "pretty quickly" it tells me that you have no idea what you are talking about. Detonation and pre-ignition, when bad enough destroys a motor instantly. A car's knock sensors and knock retard system can accomodate some of this. It will likely throw a check engine light. There is no sort of "damage over time" concept.

Running lower than recommended fuel for 2 months is the same as running it for 2 days. It doesn't do any sort of "gradual" damage. If it is bad enough, it will do instantaneous damage. Otherwise, the knock system is compensating and retarding timing enough that it wont.

[why?]

Originally Posted by SophieSleeps

You've been listening to too many people who have been perpetuating rumors.

1. Which additives do they put in? What do they do? I think it sounds like you are reaching on your comment. What is the "best additive"?

2. Car companies may test cars with high octane gas, but only to create a tune that is safe. Once it is safe, they run it at the recommended octane. This is standard. It would be dumb to run it the other way around.

3. It has been noted by stupid people that higher octane gives better mileage. What is the reasoning behind this?

4. Running lower octane gas than recommended can definately do damage to a vehicle. It's because the vehicle is experiencing detonation or pre-ignition due to the octane being too low for the tune.

When you say "pretty quickly" it tells me that you have no idea what you are talking about. Detonation and pre-ignition, when bad enough destroys a motor instantly. A car's knock sensors and knock retard system can accomodate some of this. It will likely throw a check engine light. There is no sort of "damage over time" concept.

Running lower than recommended fuel for 2 months is the same as running it for 2 days. It doesn't do any sort of "gradual" damage. If it is bad enough, it will do instantaneous damage. Otherwise, the knock system is compensating and retarding timing enough that it wont.

1. How the heck would I know. That is prolly one of the most highly guarded secrets by each oil company.

2. You misunderstand. Car companies use the highest octane gas to supply MPG ratings to consumers. I believe the EPA does as well, I read this somewhere and I can't remember, and for some reason the Fuel economy guide omits completely how they test cars.

3. It has been noted in testing that higher octane gives better gas mileage. The latest simple test was by a journalist and it is on a thread somewhere on the board.

4. Yawn. Oh no, I said something you didn't like, therefor I must not know anything. Yea, if you say so.

And you are again simply wrong about lower octane fuel causing instant destruction. What you are saying is the second a little bit of lower than recommended octane fuel enters an engine it will blow up. That of course is just wrong. An ecu can deal with lower than needed octane for a while, but that will prolly cause detonation, etc. Not all detonation causes the engine to catastrauphically blow up, most detonation just slowly weakens the engine. That is why old cars backfire more than just once.

BTW, as you have noted higher octane gas resists blowing up until the engine wants it too. That is why you can get better power and mpg out of it. Lower octane blows up whenever it feels like.

[SophieSleeps]

Originally Posted by why?

1. How the heck would I know. That is prolly one of the most highly guarded secrets by each oil company.

2. You misunderstand. Car companies use the highest octane gas to supply MPG ratings to consumers. I believe the EPA does as well, I read this somewhere and I can't remember, and for some reason the Fuel economy guide omits completely how they test cars.

3. It has been noted in testing that higher octane gives better gas mileage. The latest simple test was by a journalist and it is on a thread somewhere on the board.

4. Yawn. Oh no, I said something you didn't like, therefor I must not know anything. Yea, if you say so.

And you are again simply wrong about lower octane fuel causing instant destruction. What you are saying is the second a little bit of lower than recommended octane fuel enters an engine it will blow up. That of course is just wrong. An ecu can deal with lower than needed octane for a while, but that will prolly cause detonation, etc. Not all detonation causes the engine to catastrauphically blow up, most detonation just slowly weakens the engine. That is why old cars backfire more than just once.

BTW, as you have noted higher octane gas resists blowing up until the engine wants it too. That is why you can get better power and mpg out of it. Lower octane blows up whenever it feels like.

Prove your statements instead of saying...i read it somewhere, or I don't know because it is a secret of the gas companies.

Maybe I'm making things worse by arguing, but someday hopefully you will actually learn about gasoline and octane. A few people in this thread went on their own to research octane and have found the truth.

You continue to push a baseless argument.

Don't mean to be an ass. Fer serious. If I come off like one, then sorry.

But really. Take a few moments and do some research on this.


You don't know anything about detonation.
Severe detonation does cause the motors to break. Minor detonation doesn't weaken anything. It is a symptom of an impending problem.

True, if you put lower octane fuel in a car, it's not going to all of a sudden break. ECU's are smart enough nowadays that they will retard timing to control knock. If the knock gets bad enough, I believe most cars will go into some sort of "limp" mode and throw a check engine light.

If modern cars did not have this, and you did put lower octane gas in the car, you will absolutely blow the motor.

Backfire is caused by deposits that form hotspots that ignite unburned fuel. A lot of older cars did this because they used leaded fuel which left dense lead residue which retained heat rather well.

Where are you getting your info?

[silverRS]

yeah im using an Ethanol blend rated at 89 octane wich is just right for the Yaris, the manual at least the Canadian one suggests using Ethanol blends.

[SophieSleeps]

Originally Posted by silverRS

yeah im using an Ethanol blend rated at 89 octane wich is just right for the Yaris, the manual at least the Canadian one suggests using Ethanol blends.

That is actually one thing that may decrease your gas mileage...since ethanol decreases combustability of gasoline...

I think all of Canada is on some sort of Ethanol/gas mix right?

[argylesocks]

i just checked with the toyota chat line... they said for US, they recommend 87 octane for all Yaris.

[TRD_Yaris]

do you guys have 87 or 89?? here in texas we get 93 octane as premium, but i can't remember what the regular unleaded is..

[argylesocks]

Originally Posted by TRD_Yaris

do you guys have 87 or 89?? here in texas we get 93 octane as premium, but i can't remember what the regular unleaded is..

here in new england

regular = 87
midgrade = 89
premium = 93

[07WYarisRS]

Rule of thumb is use only the octane needed to prevent knock (detonation)
Anything higher then that and you lose HP and mpg. BUT
Most of these rumors about high octane fuels do not even apply to modern EFI engines. Carbureted engines only folks...

First off burn rates between high octane and low octane can be and often are the same. The difference is the flash point.
Flash point is the temp the fuel is ignited. With too much heat (compression) the fuel will be ignited before the spark plug ignited the mixture and that causes pre-ignition and detonation.
Most factory cars out there can run on low octane, some recommend higher octane for turbo and supercharged cars. With EFI cars today the ECU uses readings from sensors like the o2 sensors and knock sensors. If the engine starts to knock because of low octane or even high loads using high octane it does two things. #1 it pulls the timing. #2 adds more fuel.
With a carbed engine the engine would just knock until it fell apart...
With EFI systems there is no need to run a higher octane fuel unless you running crazy compression and high boost levels.

WFT is the point of building an econo box that requires the most expensive octane fuel. Give your head a shake people...

FWIW high octane fuels do not have more additives.
They contain fewer additives that promote detonation.
Octane boosters do not add octane. Most only but up the rating 3-7 points witch is less then one octane level. Octane booster do however contain additives the remove or neutralize free radicals in the fuel that promote detonation and pre-ignition.
It’s the additives in fuels that change the burn rates not the octane.

These engine were designed to use 87 octane here in North America, anything over that you are wasting your $$$ and lining the pockets of the oil companies. Not to mention doing exactly the opposite of what the car was designed to do SAVE $$$ and be efficient

When you add high octane to an EFI car right away the car is going to run slightly rich as the higher flash point fuel is not going to burn as efficiently, so the ECU using the reading from all the sensors will adjust the timing and fuel trims to burn at the proper mixture (stoich) Regardless what fuel you use running stioch will produce the same HP and KPG
So doing so you end up with the same HP and MPG but less $$$ in your pocket at the end of each week

[SophieSleeps]

Originally Posted by 07WYarisRS

Rule of thumb is use only the octane needed to prevent knock (detonation)
Anything higher then that and you lose HP and mpg. BUT
Most of these rumors about high octane fuels do not even apply to modern EFI engines. Carbureted engines only folks...

First off burn rates between high octane and low octane can be and often are the same. The difference is the flash point.
Flash point is the temp the fuel is ignited. With too much heat (compression) the fuel will be ignited before the spark plug ignited the mixture and that causes pre-ignition and detonation.
Most factory cars out there can run on low octane, some recommend higher octane for turbo and supercharged cars. With EFI cars today the ECU uses readings from sensors like the o2 sensors and knock sensors. If the engine starts to knock because of low octane or even high loads using high octane it does two things. #1 it pulls the timing. #2 adds more fuel.
With a carbed engine the engine would just knock until it fell apart...
With EFI systems there is no need to run a higher octane fuel unless you running crazy compression and high boost levels.

WFT is the point of building an econo box that requires the most expensive octane fuel. Give your head a shake people...

FWIW high octane fuels do not have more additives.
They contain fewer additives that promote detonation.
Octane boosters do not add octane. Most only but up the rating 3-7 points witch is less then one octane level. Octane booster do however contain additives the remove or neutralize free radicals in the fuel that promote detonation and pre-ignition.
It’s the additives in fuels that change the burn rates not the octane.

These engine were designed to use 87 octane here in North America, anything over that you are wasting your $$$ and lining the pockets of the oil companies. Not to mention doing exactly the opposite of what the car was designed to do SAVE $$$ and be efficient

When you add high octane to an EFI car right away the car is going to run slightly rich as the higher flash point fuel is not going to burn as efficiently, so the ECU using the reading from all the sensors will adjust the timing and fuel trims to burn at the proper mixture (stoich) Regardless what fuel you use running stioch will produce the same HP and KPG
So doing so you end up with the same HP and MPG but less $$$ in your pocket at the end of each week

^ someone who knows his stuff.
I hate it when people use high octane gas in their cars and claim they "feel" a difference. I feel bad for them.

I don't necessarily agree about higher octane = loss of power and fuel efficiency. What is your reasoning behind that?