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i normally used 87 regular pump but few days ago, i decided i value my civic and fill it up with some greater fuel. i would do this probably once a month...i usually track my mileage and i came up with about 80-90 miles right when the gas light came on with 5 gallons of 89 octane

normally, i would get 130 miles easy on 87 regular with 5 gals, but this was interesting. im thinking it was because my civic ran more 'rich' thus using more fuel?

i really dont know if their is an performance difference between the two fuels, but maybe someone can enlighten me on that issue?


til then, should i keep feeding my civic 89 octance once a month to keep the fuel system clean and whatnot? how about days i plan to run the car hard...should i consider 89 octane?

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

Read that article its good information on fuel octane ratings, really all octane is is how much a fuel can be compressed before igniting. (Diesel engines use compression to ignite fuel, while gasoline engines use a spark) I dont know if that helps but read that article to find ur answer

 
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i used to use 89 when i had a higher compression engine and got the highest mileage ever. but now that i'm back to stock I only use 87. Higher octane is more for sports cars and performance tuned engines like the rsx type s and others than use a higher compression ratio. 87 is what a civic uses.

 
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weird ... I got my best milage ever with 89.

my car bogged a lot with 87 with my d17...

 
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but our cars don't need it. the only reason i can think of is the stock plugs running hotter than they should and causing minor preignition or something.

 
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gas mileage has alot to do with when and where your driving.. if u catch lights.. if u dont

 
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i examined both tanks with city driving. same areas of roads, etc.

i didnt drive any different, if anything, i idled my car on the 87 regular for like 30min for stereo play so my battery wouldnt die.

 
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I use 93 octane, no problems with mileage and car runs better.

 
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Difference between 87 or 89 is not significant! If you continue to put couple of times 89 in tank and do the average, you will see no difference between 87 and 89.

 
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just use 87 and some techron injector cleaner every once in a while. i get about 34mpg city consistently and thats what i do. even when i drive it hard, i still get over 30 city.

 
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i def use 89 from the day i got my car till now. dont pay much attention to my gas mileage but thats prob b.c i have intake, exhaust, and cat which kills my gas mileage. ill prob c wat i get when i fill up with 89 next time. the only reason i use 89 is b.c i have seen wat 87 does to a car. my friend was using 87 for the longest time and he started to have valve knock so i told him to use 89 nd see if that helps nd boy did it. valve knock went away and the car ran smoother than ever

 
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was that on a civic? seems very hard to believe since the car was designed for 86.

 
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Honda engineers know more than anyone on this forum. They recommend 87, so use 87. 89 and 93 are for higher compression engines. You are just wasting money putting in more than 87 because the gas savings (your MPG will probably actually sufer) will not offset the fuel cost.

 
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i use 87 since the car came out from the dealer...i used to put 94 on my cav...thought that it was gonna do me good but i was wrong and it toasted my catalytic converter...and failed my emission - now i learned my lesson! stop wasting ur money and follow the manual.

 
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Have used 87 and 89 exstensively. Better mpg and performance with 89.

 
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I know 3 of Honda's engineers... They just laugh when people ask them what octane to put in their car, then they through the owners manual at them and say read it!

Really though, if you know what octane means, you would understand that it will do nothing. Now switching gas stations may do something.

 
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What do those three Honda engineers say when you tell them you put FP 60 in your gas tank? Do they through you and your owners manual out the door?

 
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I'm a chemical engineer, I know more about gas and oil than they do And FP60 and LC20 is one of the few additives that topologists actually recommends.

BTW, the second part of my statement wasn't directed toward you, but rather everybody saying that 93 octane is better.

 
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Our civics are economy cars. We have VTEC-E for a reason. Honda designed our EMS or ECU to run off of 87. No matter what octane you run, your factory ecu will run as if it were 87 octane. So basically don't waste your money. After all, it's a freakin civic.

 
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If you are a chemical engineer, you should know how to spell tribologist. And I seriously doubt that you, or the tribologists you allege to know, know more than the Engineers employed by Honda Corporation.

 
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I don't claim to know any tribologist, I only sent my oil out to them and talk to them once in a while on the phone about the results.

As for beleving me, I really don't care if you do or not But here is my name the school directory LINKY

I'm a grad student working on my PhD, if you don't believe, I'll go home and cry for 40 days

 
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By the way, your original post, that you edited, had the word tibolist. So don't get cute with the topologist slight of hand. Surely, you've seen these words in the course of your work more than once.

 
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ouch, it's f'n fuel, and the recommended is 86, that's that. More octane won't do shiat, it's in your head and you're wasting your money. Don't you think if the damn car got better mileage on say 93 octane, they would've used that to gauge the MPG and also recommend in the manual?

 
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Yes, because I remember every word I see

 
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Waste of money to put anything higher in unless your engine is tuned for it. Now in some older vehicles, I know that putting a higher octane in can make it run a little smoother (I dont claim to know anything technical about any of this, just know in my past experiences with an old 350 it ran much better on 93 not 87 and didnt ping anymore) but on a civic, its made for economy, so use economy.

 
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this topic has been talked about before again and again if you put anything other then 87 your wasting money..... 89 does nothing it's just in your HEAD!! do you really think honda would put 87 if 89 ran better???? maybe back in the day but todays cars are made to run better and have higher mpg on lower octane....

 
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hmmmm i guess ill stop using super gas than if it does nothing

 
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Your gas millage should not be affected by using 89 instead of 87. It will only if you have high performance plugs and wires. The higher octane is designed to be a little cleaner. It can go both ways, but if you are running a stock Civic, then use the 87 because the car is built for 86 or 87 depending on your engine. If you have a good amount of mods, then use the 89.

 
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all gas is clean. you want better gas, use the fp60. you guys crack me up 89 does not run better nor does it give better mileage. If you havetrouble running 87 in your civic, let me tell you something. Its not the gas that has the problem.

 
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well ... just some food for thought.

D17a2's recommend octane is 87. Compression ratio is 9.9:1

B16a2's recommended octane is 91. Compression ratio is 10.1:1 (iirc)