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i learnt from a friend who learnt from his chemistry teacher that you should alternate between gases - between 87, 89 and 93. According to his chemistry teacher, one octane provides the engine what the other octanes dont.

is this true?

 
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you should stick with 87, thats what the civic engine was designed to use. higher octane is for performance cars with hi compression ratios. and a chem teacher is the wrong person to ask anyway.

 
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if you put anything besides 87 in your car you are considered a dumbass, unless you are boosted or swapped

 
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agreed, or just hooked up with internals

 
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I think some gas stations overrate their gas. I put 89 in from a shitty place and it ran like 87 from sunoco. It is also pretty much fact that the cheaper gas around my area gets you noticably lesser mpg. I am not sure though.

I would just stick to the more upscale busy gas stations, that is your best bet.

 
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So it's somewhat stupid for me to use 89 in my car? I usually use 89 in all the cars i drive and i'm just used to using that. Would using 89 actually cause problems with my car?

 
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your car is designed for 87, so use it

 
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No offence or anything though, that really didn't answer my question. Will it harm my car if i use 89 instaed of 87. There is really nice price difference where i buy gas between 87 and 89.

 
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the higher the octane the harder it is to combust.
87 octance combusts at a lower compression ratio/temp then 92 octane.
So if you're running anything higher then 87 on your car (unless you're running boost) you run the chance of poor combustion and loss of power. Not to mention puting a dent in your wallet for no significant reason.

 
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Yeah, but I think some gas stations overrate their gas, and that is why some people have reported their cars as running better with 89.

If the gas really is 89 then you are wasting money. You can also damage your cat because not all of the gas is burned up. But like I said from the stories I have heard and my personal experiance, cheaper gas stations are a waste of money.

 
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Thanks for the answer guys, looks like i'll be saving that 1-2 cents a gallon of gas now.

 
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ya it will cause more harm to use higher octane like extra carbon deposits and power loss eventually.

 
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You serious?

 
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Ok Gearbox your saying that because our cars are designed to run on a les productive rated gas that we can not or should not use a BETTER gas and burn fuel BETTER and our car cannot perform BETTER on 89 or 93 octane that is actually designed BETTER for CLEANER burn in the combustion chamber??? Also that it leaves exes carbon deposits? Does anyone on this form have the injectors and combustion chambers cleared and cleaned chemically (by professionals) if so you know the white smoke is carbon deposit burn out. Well I ran 87 octane the first 40,000 miles for break in after that I moved to 93 and when my combustion chamber is cleared/cleaned I have far less white smoke and for not as long than the previous 40,000 miles.

Gearbox
So my question to Gearbox is wear did you get your information and can you share your source?!?!?

 
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better gas? there's nothing better about it. its higher octane, designed to be used in higher compression cars to prevent detonation. putting higher octane in a civic won't make more power, end of story. It won't burn better, in fact it will probably burn worse because the engine cannot compress all the fuel during the cycle. cleaner, come on. has nothing to do with octane. use a fuel additive like fp60 if you want clean gas. i've opened my motor too and didnt see any difference. i was using 89 when i was at 200psi compression instead of stock 135, so i'm sure it made a few hp extra. i only used 89 on that head, then when it blew i went back to stock with 87 and the carbon actually looked about the same as a year ago when we opened it up.

93 octane, please tell me you have a turbo on your car.

 
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It would have been turbo this weekend but this problem with the S2tC **** has probably delayed that and I go back and forth from 87 to 93 every other fill up.

 
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okay just so you know 93 now doesn't do anything other than waste money. but for turbo you'll need it all the time.

 
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hahahahahah you put in 93 octane..........hahahahahahahaha

 
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Why are you laughing, your making an *** out of your self.^^^

But Gearbox, yeah I figured every thing else has to be broke in I figured going from 87 to 93 octane should be a gradual merge as well.

 
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im not making an *** of myself, you are the *** putting in 93 octane on a NA civic

gearbox just said it doesnt do anything but waste money, so what the hell are you talking about...just use 87 unless you like wasting money

 
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well yea its gradual, the ecu needs some time to adjust its sensors to try and make use of higher octane. usually this means timing is affected, which generally causes a loss of power compared to just using 87 (actually the car was made for 86 but there isnt much difference).

 
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Ok that’s pretty much what I thought Gearbox, Gearbox go to my cam thread