thanks
cosmo93940

It'll run on whatever you put in it. I use 87 and have no problems.

Let the owner's manual be your friend. :wink:

we do not need anything special. (read the cheap stuff)

The book says 87 but if you run midgrade you will get slightly better fuel mileage. I'm surprised with 10 to 1 compression ratio that it doesn't call for a higher octane. :?

Just use 87. Mid grade won't change your fuel economy.

neither will super

actually super may make it run worse.......

Just use 87. Mid grade won't change your fuel economy.

Some vehicle are so inefficient it doesn't matter BUT I have noticed better mileage with a higher octane. FACT!!! And with a high compression ratio it will run better with premium, but you don't have to use it unless you want to so sometime the premium has extra cleaning agents in it so you don't have to use an injector cleaner.

Just use 87. Mid grade won't change your fuel economy.

Some vehicle are so inefficient it doesn't matter BUT I have noticed better mileage with a higher octane. FACT!!! And with a high compression ratio it will run better with premium, but you don't have to use it unless you want to so sometime the premium has extra cleaning agents in it so you don't have to use an injector cleaner.
ALL modern fuels have the additives you're talking about. I have noticed NO improvement by running Mid grade, and I have noticed a negligable DROP in mileage by running super. Also, not all High compression engines will run better on High test (91 in CA, 92 or 93 elsewhere). I NEVER use "injector cleaner"; it's snake oil. But if you do store your car, you SHOULD use High test in conjuction with a stabilizer. that is the only time high test will see my tank.

If you use injector cleaner on a regular basis it keeps the injector buildup to a minimum. Used it regularly on a Ford van and after 500,000 miles never had to have the injectors profesionally cleaned, so I know it does something

if you run midgrade you will get slightly better fuel mileage.

Let's say that's true, but do you get enough extra mileage to make up for the higher cost of the fuel?

In theory you should get better mileage using a higher octane because the engine will produce more power. More power produced means less fuel needed to obtain and maintain the same speed. However, in my experience the difference is negligible and usually isn't worth the extra money.

Regular: 10Gal X $1.70 perGal = $17.00 10Gal X 34MPG = 340Miles
High Octane: 10Gal X $1.90 perGal = $19.00 10Gal X 35MPG = 350Miles

If the car actually managed to get 1 more mile per gallon you can see the difference is only 10 more miles for a price difference of $2.00. It doesn't make enough difference to justify the money unless the change is much more significant and I've never seen it or heard it.

actually the computer retards your timing a bit when you run super so your car will actually run worse and usually get worse mileage...try it run a week on super then a week on regular

In theory you should get better mileage using a higher octane because the engine will produce more power.

Wrong wrong wrong. You don't understand octane.

High performance engines require higher octane to compensate for higher compression and more radical valve and spark timing. Higher compression engines generate more heat (pressure = heat, that's basic physics). That heat, along with spark timing that's set a hair sooner than on moderate performance engines, can cause the fuel/air mixture to detonate too soon -- predetonation. This can cause engine damage since the piston is still trying to move up while the burning/expanding fuel is trying to push it down. To prevent this, octane ratings are increased so the fuel can withstand more heat and pressure before igniting. In other words, high octane gas is HARDER TO BURN. It's a cure for a problem, not a magic power juice.

Now, even though the compression ration on the xB/xA/Echo engine is on the high side, its computer automatically adjusts spark and valve timing to prevent predetonation. I suppose you could argue that with higher octane gas there's less likelihood of predetonation, so the computer could back off the timing less, keeping the engine closer to its optimal power band. But then you're left with the cost/benefit question. Using your numbers, $1.70/gallon gas at 34 MPG = 5 cents per mile. Meanwhile, $1.90/gallon gas at 35 MPG = 5.4 cents per mile.

In theory you should get better mileage using a higher octane because the engine will produce more power. More power produced means less fuel needed to obtain and maintain the same speed. However, in my experience the difference is negligible and usually isn't worth the extra money.

Regular: 10Gal X $1.70 perGal = $17.00 10Gal X 34MPG = 340Miles
High Octane: 10Gal X $1.90 perGal = $19.00 10Gal X 35MPG = 350Miles

If the car actually managed to get 1 more mile per gallon you can see the difference is only 10 more miles for a price difference of $2.00. It doesn't make enough difference to justify the money unless the change is much more significant and I've never seen it or heard it.

$1.70 per gallon? where are you seeing gas for that cheap!? Or are you just using that as a figure? lol.. It's still like $2.09 for regular here in S.FL.

Gas is about $1.70 per gallon here in northern SC.

Old Punk,
I never said higher octane fuel was "magic power juice". Just as you said, a car using a higher octane fuel will not back the timing down as much. More timing means more power. Hence the over-simplified comment "In theory" the car will make more power when using higher octane fuel.

In theory you should get better mileage using a higher octane because the engine will produce more power. More power produced means less fuel needed to obtain and maintain the same speed. However, in my experience the difference is negligible and usually isn't worth the extra money.

Regular: 10Gal X $1.70 perGal = $17.00 10Gal X 34MPG = 340Miles
High Octane: 10Gal X $1.90 perGal = $19.00 10Gal X 35MPG = 350Miles

If the car actually managed to get 1 more mile per gallon you can see the difference is only 10 more miles for a price difference of $2.00. It doesn't make enough difference to justify the money unless the change is much more significant and I've never seen it or heard it.

$1.70 per gallon? where are you seeing gas for that cheap!? Or are you just using that as a figure? lol.. It's still like $2.09 for regular here in S.FL.

1.84 for reg.
2.07 for super

if there was only a .10 cent diff (or one dollar more per tank)between reg and super i would run super all the time.
by me the diff is about .25 cents per gal. (or 2.50 more per tank)

Oh man where you guys are at its pretty cheap for gas....over here in L.A. its $2.41....In my box i always put 89....but im starting to think about putting the cheap stuff...LOL...

First off Xb's only need 87 octane. They should never be damaged on 87 regardless of weather or engine load. I think the conversation has turned from what they need into what they can put to good use.

You know...there's alot of people making assumptions on here and regurgitating what they've read. It really depends on how Toyota engineers programmed the computer. Who knows if they built & locked the timing maps around 87 octane ONLY or if they allow the computer to advance timing based on fuel quality which should allow for a couple extra HP. I'm pretty sure none of you have the inside information to know for sure. Two ways to find out though. Obvious one is to dyno at the end of a tank of each fuel you're trying to test. The other way would be to get an OBDII datalogger and log timing Vs. RPM on a 3rd gear pull on the different fuels. If you get more timing advance with the 89 then you're almost certain to be making more power. Not much more but more just the same. I have an OBDII datalogger for Japanese cars but this just hasn't been important enough to test out.

like I said test it

Trevor is making total sense.. I for one would like to know where to look for my "fuel quality sensor"...

and to throw in the info... we have 85/87/91 here in Colorado... and 85 is overkill because WE HAVE NO FREAKIN' AIR....

octane is not a measure of power, it is a measure of stability... PERIOD... go read the gas faq... it is listed in the links section...

Some vehicle are so inefficient it doesn't matter BUT I have noticed better mileage with a higher octane. FACT!!! And with a high compression ratio it will run better with premium, but you don't have to use it unless you want to so sometime the premium has extra cleaning agents in it so you don't have to use an injector cleaner.

I 2nd that. At least that's how it was in my old CRX. I'll haven't tested the Scion to find out if it's the same. But a couple years ago I took price per gallon, mileage per octane achieved. And it turned out being cheaper using super (went father per dollar). And the super makes your ride a lil pep-er as well. And with super+octane booster I could actually feel a difference in power. But that was in a swapped CRX. Other cars may react a lil differently though. And for who ever said super or higher octane will make your car run worse, you need to do a lil more research.

In theory you should get better mileage using a higher octane because the engine will produce more power.

I don't know where your 'theory' came from but it is totally wrong. Using a higher octane gas than the mfg calls for will do NOTHING for your power. If you use a lower octane than the mfg calls for you'll lose power- that is true.

Bottom line- use whatever gas the mfg tells you to. In this case 87. End of debate.

no you need to research if you understand obdII systems :roll: :roll: :roll: :roll:

http://auto.howstuffworks.com/question90.htm

So those of you that are still saying 87 octane only...how do you know for certain that the computer isn't programmed to add any extra timing on higher octane fuel? Have you tested it on a dyno or with a datalogger?

Companies either reccomend regular or premium fuel (with very few exceptions (See the new EVO requiring 93). Manufacturers avoid requiring premium fuel because that can put a dampner on sales for all but the people that don't mind spending some extra money on performance. On cheap cars like the Xb that can especially hold true. Just because the engineers programmed the engine management to run safely on regular gas does not mean that they didn't set it up to advance timing when higher octane fuel is introduced. Example? My old 98 BMW M3. It required premium fuel which is 91 octane by definition. I live and race at 3,075' altitude and we used to have 93 octane locally. With 93 it went 94.3 MPH trap speeds in the 1/4. After 93 octane dried up and the switch to 91 trap speeds dropped to 92.4 MPH. With 100 octane fuel in the tank many people on the BMW boards have picked up 1.0-1.5 MPH over 93-94 octane in practically bone stock cars. It's well documented that the E36 and newer M3's continue to gain power from 91 to 97 octane. Above that returns dry up. But there you go. 91 octane gets you bottom of the barrel timing advance but the car still runs safely with it. The problem is power is not all it could be since the computer is just doing its best to keep knock at bay and the engine safe. Add better gas and that particular ECM is programmed to continue advancing ignition timing up to the edge of detonation or until the pre-set max is reached which is usually hit around 96-97 octane. The question still remains of how the computer is programmed in the Xb. You may be right...it may not advance timing past 87 octane levels...but until somebody actually tests it out in a semi-scientific way you can't say that for certain.

Let me say it again though...nobody needs to put anything other than regular gas in your Xb. The car should never have a problem with it.

like I said it may make it run worse and to test it

My box has only used super (CA 91 octane) since day 1, and has had no problem, nor do I see a lack of perfomance, I also have driven a box that only has had 87 octane since purchased and notice no difference.

My .02

see i use Cam II purple, 114 Oct. Help keep from detinating w/ my 15:1 compression ratio. :-P nothing like $5 a gal.

I will be running an OBDII analyzer full time in just a few short weeks... I will report back my findings... I will eat the WASTED 20 cents/gallon for a tank or two to show what the system is running...

here's an example of what I am referring to...
http://obddiagnostics.com/

it's 38 degrees outside and my hands are about to fall off from installing my new XMDirect...

93

we do not need anything special. (read the cheap stuff)

Speak for yourself ...... :lol: This comment directly from the SPED!

we do not need anything special. (read the cheap stuff)

Speak for yourself ...... :lol: This comment directly from the SPED!

for myself huh....i am required to use super now.

cosmo93940

i think you got a little mixed up there cosmo.

(he said thanks for the input in the subject)

no prob...

I will be running an OBDII analyzer full time in just a few short weeks... I will report back my findings... I will eat the WASTED 20 cents/gallon for a tank or two to show what the system is running...

here's an example of what I am referring to...
http://obddiagnostics.com/

it's 38 degrees outside and my hands are about to fall off from installing my new XMDirect...
thanks :D I am curious

use the cheapest gas you can find the engine was designed
to run on 87 it runs better on 87 you can use whaterver you feel is best for your climate and operateing conditions for me
in the north west and when i lived in ca i have allways used 87 i am a technician of 17 years (toyota/lexus/acura) i never had any problems with 87 with any of my cars

i think the point of all this is that using anything but 87 is pretty much just a waste of money. if you got 1mpg better, and save 10 miles per tank, at 1.80 a tank, you're saving $0.60. but, you're paying $0.10 more a gallon, which is a dollar for 10 gallons. which means by putting 89, you're not cleaning your engine any better, but paying $0.40 more for performance that you can't feel. i think i'll stick with my 87. just make sure you fill up at chevron or 76 :P

i think i'll stick with my 87. just make sure you fill up at chevron or 76 :P

Those 2 and Shell are the ones I AVOID. They obviously work together to keep the prices higher than they need to be. Just lllook at any spot that has those and an Arco or the few others that still give a decent price. I always buy from Safeway or Costco. Much lower prices and the gas is all the same. Ca has standards, it's not like it's coming from some mom and pop refinery...

I prefer to save the buck or more per fillup and then buying an occasional fuel system cleaner.

bp amoco is the cheapest in my neck of the woods...

Well, from reading this you can tell me 93 oct is a waste, but after running 87 ever since I bought my box back in June and recently switching to 93, I can say that the engine definitely runs smoother now than it did before, and doesn't seem to struggle or work nearly as hard going up the steep-___ hills here in PA as it did with 87.

On a side note, the gas in Japan avgs about 96 oct so mechanically the engine will handle higher octane no problem, although they may be using a different ECU special for America to handle our crappy gas. If it's one universal ECU for Japan and America though, I can't imagine that it would not adjust to benefit from using higher oct gas. Anyone know if the ECU is special for here? Just curious.

http://www.thekirkhams.com/avatars/popcorn.gif





More than you ever wanted to know about gasoline. (http://www.turborick.com/gsxr1127/gasoline.html) I'm with Old Punk, btw. My supercharged Miata has to run 93 octane, and I run an MSD ignition retard as well, but the xB is designed for 87. Anything more than that and you're wasting your money. These cars weren't meant to put out horsepower. They were meant to be economical.

The ECU doesn't change the compression ratio and that is what can take advantage of the higher octane. If you're NOT getting pre-ignition with 87, the higher octane WON'T do you any good.

But the ECU does control timing, which can be advanced/retarded by the ECU to get optimum performance from the fuel being used. Within limits, the higher the octane fuel being used, the further you should be able to advance the timing before you get pinging etc., thus better performance. Mechanically, the xB engine was designed not for 87 oct, but for as high as 96 oct to also be used in the JDM market where gas is much higher quality. It may run on 87 here and do fine, but it runs smoother with less effort on higher.

But if the ECU runs a *standard* such as 10* BTDC with 87 octane, and isn't programmed to continue running the timing up until knock occurs, then backing off, then it will *not* advance the timing. Just because the timing *can* be advanced past spec doesn't mean it *will* unless you fool the computer.

The ECU on my OBDII 1996 Miata must be fooled into allowing higher timing. You have to jump 10-gnd and then manually advance the timing with the CAS. The Miata was tuned for 87 octane and that's what OBDII knows is best for it.

The ECU on these cars was tuned for 87 octane. The base timing for the ECU is such that it runs well on 87 octane. I have a hard time believing that ECU is going to advance the timing until it gets knock. It's just going to go "Hey, no knock. They must be running 87 octane or better."

I fill up with Shell V-Power, and I do not know why, so dont ask.

-nt

But if the ECU runs a *standard* such as 10* BTDC with 87 octane, and isn't programmed to continue running the timing up until knock occurs, then backing off, then it will *not* advance the timing. Just because the timing *can* be advanced past spec doesn't mean it *will* unless you fool the computer.

The ECU on my OBDII 1996 Miata must be fooled into allowing higher timing. You have to jump 10-gnd and then manually advance the timing with the CAS. The Miata was tuned for 87 octane and that's what OBDII knows is best for it.

The ECU on these cars was tuned for 87 octane. The base timing for the ECU is such that it runs well on 87 octane. I have a hard time believing that ECU is going to advance the timing until it gets knock. It's just going to go "Hey, no knock. They must be running 87 octane or better."

I agree. It's basic science and mechanics, people, nothing more:

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.

The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.

The name "octane" comes from the following fact: When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you may have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.

It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.
http://auto.howstuffworks.com/question90.htm


The ONLY thing higher octane does is allow higher compression. Our ECU is going to fire the cylinder at the moment it gets to the optimum compression. IF the cylinder CAN compress the 87 octane air/fuel mixture to this optimal point WITHOUT pre-ignition, then HOW will higher octane (ie: able to be compressed more before ignition) help?

But if the ECU runs a *standard* such as 10* BTDC with 87 octane, and isn't programmed to continue running the timing up until knock occurs, then backing off, then it will *not* advance the timing. Just because the timing *can* be advanced past spec doesn't mean it *will* unless you fool the computer.

The ECU on my OBDII 1996 Miata must be fooled into allowing higher timing. You have to jump 10-gnd and then manually advance the timing with the CAS. The Miata was tuned for 87 octane and that's what OBDII knows is best for it.

The ECU on these cars was tuned for 87 octane. The base timing for the ECU is such that it runs well on 87 octane. I have a hard time believing that ECU is going to advance the timing until it gets knock. It's just going to go "Hey, no knock. They must be running 87 octane or better."

I agree. It's basic science and mechanics, people, nothing more:

The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.

The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.

The name "octane" comes from the following fact: When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you may have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.

It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.
http://auto.howstuffworks.com/question90.htm


The ONLY thing higher octane does is allow higher compression. Our ECU is going to fire the cylinder at the moment it gets to the optimum compression. IF the cylinder CAN compress the 87 octane air/fuel mixture to this optimal point WITHOUT pre-ignition, then HOW will higher octane (ie: able to be compressed more before ignition) help?

Everytime someone posts about what kinda gas do you use there is always a conflict. My parents have always filled their cars up with Premi Gas ('97 Nissan Quest, & '96 Hyundai Elantra). And have had zero problems, (exept the bearings on the Hyundai), would the cars be the same with 87 octane? Who is to say.. Being their spouse with a new car, I buy the same gas they do.. My fill-ups are around $20, and that is not bad to me.

IMO the people who buy 92 octane gas, buy it for peace at mind, it probably does not do a dam thing, but, why not, it will not hurt anything. I maybe wrong, but that is my take on it.

-nt

Higher octane gas equals less work for the engine in the long run and less work under heavy acceration. Also with a Cold Air Induction System that experiences a "Ram" effect you will build higher HP and TQ numbers than with a lower octane.

Higher octane gas equals less work for the engine in the long run and less work under heavy acceration. Also with a Cold Air Induction System that experiences a "Ram" effect you will build higher HP and TQ numbers than with a lower octane.

That is exactly what I have herd, but I have not seen it proved. Makes sense, and i have a CAI also :wink: .

-nt

Higher octane gas equals less work for the engine in the long run and less work under heavy acceration. Also with a Cold Air Induction System that experiences a "Ram" effect you will build higher HP and TQ numbers than with a lower octane.

You didn't read this thread before you posted did you? This is EXACTLY the incorrect information that creates these long posts.

It's not a subjective thing, "Who is to say"? The compression ratio is to say, That's who. With our comression ratio, higher octane WILL DO NO GOOD! PLAIN AND SIMPLE! Shouldn't even be a debate...

Nobody said that these cars WOULDN"T run fine on higher octane. The fact of the matter is they will not be able to gain any advantage out of it. It's money you're thowing away - worse, giving it to the Big Oil companies...

Higher octane gas equals less work for the engine in the long run and less work under heavy acceration. Also with a Cold Air Induction System that experiences a "Ram" effect you will build higher HP and TQ numbers than with a lower octane.

you're not even close... this thread is just about out of wind...

seriously people, go read the GAS FAQ

http://www.cs.uu.nl/wais/html/na-dir/autos/gasoline-faq/.html