Correct
Not always, but most of the the difference is in brand not Octane.

And 10.5:1 is low compression? The highest compression I can think of at the moment on a stock car is 11:1 so I would say 10.5:1 is the high end. Funny thing, I remember when anything over 9:1 the general consensus was you had to use higher octane to prevent knocks(especially in the summer), not saying this was correct, just one of those everybody knows things...
But if Toyota in it's wisdom says 87 is fine then thats what you should use.
I laugh at Civics.
"guaranteed", gosh that word just never looks right.
agreed..

Here's a better reason to use the recomended octane...Octane, by definition, is the resistance to burn or detonation. The higher the rating, the slower the burn when ignited during the compression burn cycle of the piston. The higher octane allows for better control of burning for high compression engines. So we want to match the correct octane rating of the gasoline to the engine design to ensure complete burning of the gasoline by the engine for maximum fuel economy and clean emissions.
When you use a fuel with a higher octane rating than your vehicle requires, you can send this unburned fuel into the emissions system. It can also collect in the catalytic converter. Not burning all the fuel is pretty much a waste of all your extra money you are spending on higher octane fuel, and if any of the fuel is burning up in the exhaust system you get soot all arount your exhaust system.

 

I don't know how to jump into this subject, it is always a hot topic.
I will try to explain why I use high octane gasoline.
ONLY from big makers of the stuff like Mobil, Shell, BP.
First off, I would use the lowest, cheapest gas my car will PERFORM with. Unfortunately, I drive all my cars like I just stolen it. (5 speed) Top speed 112 @ approx 5900 rpm, avg mpg 31, mixed driving, mostly very hilly, still stock wheels, engine. I also do not like my knock sensor to have to function, I like to do it if possible and correct the conditions. I have, 93 octane, no more knock.

The design of most cars today are made to function on the worst possible gasoline. The bright side is they were also made to peform. The creation of the knock sensor allows everone to be happy. If you notice on page 118 & 119 in the box book, it explains the function of the knock sensor, well not really.
It works from vibration from the multiple explosions going on in the combustion chamber under heavy load/demand. A slower burning gasoline,( low octane). The engine needs to knock for the knock sensor to sense what is going on. Knocking is the sound of your pistons getting several wacks at a time insted of one. Not a good thing.
That is why yout can sometimes hear it. Once the brain box gets a pre detention signal it retards the timing until it goes away. Sometimes it can't go far enough, so you go to the dealer who will manually turn it for you to give it more room in the low octane gas zone.
Unfortunately, most brain boxes today are created to develope memory over time,
(Toyota tuners step in please). It learns based on driving conditions, gasoline quality, drivers easy, or stomping foot. It will learn to stay towards retard or advance, based on its repeted information form air flow sensors, tempture, oxygen sensors, ext...
This is why someone who has used low octane for 3000 +miles puts in his firs tank of high octane and doesn't notice a thing. Sometimes worse gas millage.

Premium gas is roughly .20 more. I figure I will need about 300 gallons of gas for my box in one year. That is about $65.00 a year. Or 1 month for dish. No biggie for me.

Toyota tuners, What is the compression ratio?
I am guessing it is about 10-10.5 to 1.

Rob

 

i hope u can awnser this one what about those fule aditive in the stores do thay do anything for the car... u usualy put in one fule injecter cleaner per month is this good or bad?? what about the octan boosters and the 0 -60 booster whats up with those are they any good??

 

I am not a beliver in additives. I can not prove all, but I can dis prove several.
Older cars can use a good fuel system/ injector cleaner with some good results but you should always change the oil after it runs through.

I have had no luck in my 1.8 GTI powered 1970 VW bug with drop in boost additives.
After the turbo went on last year, and I lowered the compression, backed off ALOT on advance. I still get a little knok. Now when I'm at the track I'll add about half 108 octane to 93 pump gas. I can get way more advance with no knock.

Along the lines of maufacturer recomends: We must remember that Scion as well as all car manufactures, are in the business to sell cars. Therfore, a low end car company or most all manufactures will NEVER tell you to use premium gas, or change the oil more often. They push the mark to keep operation cost low to sell cars.
If they didn't, companies like Consumer reports would tare them up, and no one would buy the cars.

So use you box book wisley.

Rob

 

Congrats on th placebo effect - I'm glad you like wasting money, it helps the economy.

 

Nothing wrong with putting a name brand fuel injector cleaner in, like Chevron Techron. Once a month is excessive, but it shouldn't hurt anything. Don't waste money on octane boost.

If you get your gasoline from Chevron or ExxonMobil, BP or any of the big gas stations then there is already a patented additive package in the fuel, you should not need any fuel additives at all.

 

If you read the owners manual, or know anything about the car you will see that the compression is 10.5 to 1. You can run 87 oct. but the computer retards the timing in order to run. I have never run anything under 91 oct. and I have never had another echo or scion even stay close to me, if you want real fun you can run 104 oct. race gas, smells good too.

 

i think you have more to worry about than your 'pinging'...

 

ok if you think your car is knocking, it shouldnt, take it ti the dealer. yor car should be under warranty

dont waste your money with high octane. just let the dealer fix it because if you say your runnin high octane they wont be able to diagnose the problem untill the car is full of 87.


warranty is your best friend. thats why they are new cars. they come with warranty.

 

An Ode to Octane

If you want to know what octane you need,
Its 87, yes indeed.
But if higher octane seems better than low,
then go ahead and waste your dough.

 

The computer does NOT retard the timing to run on the recommended 87 octane, nor does it advance timing when you fill up with 91.

Imagination is a powerful thing. Have fun with your race gas.

 

Really? on www.scion.com it has it as:

Compression ratio 9.6:1

maybe you have the wrong forum...or maybe i do!!!

 

I'm skipping ahead here and this may have already been answered, but would like to chime in (to at least reinforce it):

Your vehicle is designed specifically with a certain octane in mind. If its designed for 87, you should use that. In addition, using an octane much higher than that called for in the engine is more than just a waste of money, it can be harmful in the long term. High octane fuel with too low a compression ratio and the wrong spark timing may not burn completely. These can lead to deposits building up in the combustion chamber that ultimately can cause "hot spots" (and plug fauling) that can cause detonation if you try to go back to the fuel the vehicle was designed for. As such, you can become an "octane junkie" creating a need that shouldn't be there in the first place and is not providing a performance advantage. Now regarding performance, if you DO want to run higher octane fuel, you should see if there are any chips designed for that engine to alter the timing. You can gain a modest amount of power that way. *note* I don't know of any vehicles that can recognize a higher octane fuel and alter the ignition timing accordingly. And while most can and do pull timing when used with too low an octane, this is typically in response to a quite insensitive knock-sensor from what I know.

Regarding detergents: The law also mandates a minimum amount of detergents in each octane regardless of the manufacturer (these actually all come from mostly the same refineries and the various distributers take care of how well its transported, the additive packages, distribution, etc). They put the same detergents in their high and low octane gasses. Remember these are required by law and its not cheaper to come up with two different pacakges. And there is no mid-grade octane produced by the way, it is simply a mix of high and low octane fuel to arrive at the middle-ground with an appropriate middle-ground price.

HOWEVER, you may not be experiencing a placebo effect here, and I do believe you that you are experiencing a better performing and smoother running engine... the reason is because you mention you were experiencing detonation with the correct fuel. Something is wrong with your car. Please bring it in to the dealership and demonstrate the knocking. Typically this sounds like marbles shaking around in a metal can (is this what you hear?). Get that fixed and then use the proper fuel and you should be good to go. You may wish to try 87 at a different station though, as its possible you just got one bad tank. If you aren't sure what good fuel is, see: http://www.toptiergas.com/index.html

 

I just use whatever the manufacturer suggests.

If the manual says use 87 octane, that's what you should use.

Otherwise, you're just wasting your money.

 

I've got some beach front property in Nevada I can sell you. Reeeeeeal cheap too!



j/k. Hey, it's your money.

 

i use to fill up my xb w/ 91 untill my walet started knocking...
stay with 87 man...

 

Ducman hit the nail on the head.

If you car is running better on 91 octane then something is wrong with your car.

 

once again, more clarifaction.... i never said my car would never work on 87 octane.... it runs fine.... but for some reason, the car seems to have a small amount of drivability added when you use higher octane.... but yes, it's my extra $2 i spend... (1.89 for cheap, $2.08 for high).... but i've been running low octane for 28k miles so far.... no problem (except a small knock every once and a while) and i put a total of 4 tanks of high end stuff.... a few times changing between to make sure it wasnt a fluke.... say what you will.... but i feel it does do a small amout better..... plus i like how i get more (your stupid) reactions than that one guy who drives w/o his seatbelt.... i guess fuel is more important

 

Some people post too lenghty of replys. FYI
I always use BP 87 or Quiktrip 87.
No need to waste money

 

there are other considerations when choosing octane as well...
Brand, temperature, humidity, altitude, and drastic weather changes are also something you might take into consideration...

most people who don't experience much of a difference live in nice dryer climates.. unfortunately I live in jersey/philly/delaware area... close to sea level with lots of humidity and wind... so i run better then 87...

if your car knocks check the oil, you might be running a little low...