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yeah but there's never been proof that a persons EM2 broke from using 93 gas right?. it's just bad for the owner of the car cause he/she is breaking their wallet.

 
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no ive only heard of injectors failing on other cars. but the carbon, theres no way to tell except opening up the engine. but it happens over time, not just in a year.

 
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well. is it too late for my injectors?. have i already caused damage to them for using premium gas for like 13 to 15 months already?.

 
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feeling good?. i haven't had a bad thing happen once to my car from using that 93 premium gas. i have to wait though untill my cars tank is empty from the premium gas thats in it now. but i could swear that there was a reason why i switched over to the premium gas. i thought that the 87 gasoline was crap on my car. felt like my car ran badly or just a bit more jerkier with the regular gas in it. if i start to feel like my car's acting up after i put that regular gas in it. i'm switching back to premium.

i mean, my car doesn't ping or clank with this gas. it idle's really good and even. i can't seem to understand why premium is bad for our cars. besides to point that it's hard on people's wallets. i dunno.

 
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if your car pings with 87, you have serious motor problems.

 
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it doesn't ping. i meant that it feels different with 87 octane. it feels that way. maybe it's just me. my word usage sucks LOL. i hope you guys are right about my car being ok when i end up going back to Regular 87 gasoline. and if you guys say that my cars ok after a year now with premium gas being used and suddenly going back to regular. than i'll take your word for it. afterall. we all have the same cars. i could've swore that my manual for my car says "87 octane or higher".

 
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It seems you cannot read too. Learn to read and you will see why it is no good for the engine. Lock this already.

 
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oh? who do you think will lock this? ya.

 
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This is getting old. It's a waste of money. It does nothing for a d17 engine. When I did a couple of tanks it actually decreased gas mileage. It's tuned for 87. Even with my swap/turbo I notice less gas mileage with 94 then with 91.

 
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no one

 
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OK! point taken!. i'm just asking questions. it's not like i can do anything about the rest of the premium gas thats in my damn tank!. i'm MOSTLY curious or worried about what the gas has done to my car for the year that i've been using it. or if there ISN'T any damage or malfunctions WHATEVER!. i don't want my car to start trippen after i start using that piece of **** 87 octane gas. i sure hope to hell there's no type of problems thats all. it's not like putting premium gasoline in our cars would be the same as sabotaging it. like i said before. putting premium gasoline became more of a habbit for me. i just wanted to try out the premium gas one day long time ago. and been using it eversince. thats all. but it's not really "breaking my pocket" and to add on the "poor gas milage" uhh, no, i have NOT noticed a difference. same car milage reation to both grades IMO.

 
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my bad. didn't mean to say 87 was ****. just hoping my car won't somehow react differently to it thats all. i wanna just go back to using 87 with no problems.

 
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you wont have any problems when you switch

 
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This is what you do:
Fill up with 87, open up hood, open up fuse box, take out ECU fuse, wait 2 minutes, put everything back together and start it up. The ECU will then be reset and it should work like normal with 87. I don't think there will be any difference either way.

 
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cool. maybe i'll do that. or just let it manually adjust.

 
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I've been running 93 octane on my 2k1 civic since i bought it 7 years ago. It's got 92K miles on it now. I've always used 93 on it so I can't say with definite certainty that it's running better than 87. However, I've tried running 87 as trials and it really felt ( don't talk to me about placebo effect ) that the car was lagging, as if running on 93 with only less than 2 gallons left in the tank. If you know your car, you know what i mean. I've actually been to a honda dealership today to get my car checked because i was concerned. (I've been arguing about this same exact topic on a different forum) I wanted to get my timing belt replaced, since I'm nearing the 100K mark. Because my trusted mechanic wasn't there, my car was serviced by another one and I was told (after he checked it) that i don't need a timing belt replacement for another 10k miles, although they were more than happy to do it. Then, I SPECIFICALLY asked for carbon deposits on valves and cylinder heads (acting as if i knew my stuff, which i actually don't) and they let me take a look for myself. Now, i don't know how cylinder heads and valves are supposed to look like after 92K miles, but the ones in my car were close to absolutely spotless.

Now, since i've been met with hostility on the other forum I want to point out that i'm not insulting anyone or attacking other's experiences or statement, just writing my experiences.

 
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I read 7 pages of this thread before I realized it started in 2005! I got to some post about "I just got back and now gas is over $2. Nobody will be able to afford to drive at that price"



But You are not the only one. Maybe 2 versions of cars are made. The ones that don't benefit from premium and those that have magic pixies under the hood and makes it better.

Brand and Octane matter. And yes I know the defintion of octane. Using Shell V-Power (91 here, also 8000-10000 feet above sea level) I get between 38 and 42 miles per gallon driving slowly. When I fill up at the cheapo station with 85, I barely get 32mpg. And I can notice the difference. Not on just driving around, but when I get on the interstate and use the interstate's onramp I feel the difference. THe only time I have filled up with the 85 is the first time gas went over $3 a gallon. It was $3.50 here for regular and premium was $0.35 more. So I filled up cheap for about 2 months. Hated it, and I noticed it. Also I had a friend in my car, and he also noticed something a bit "lagging" and the type of gas you use in your car doesn't exactly come up in conversation, so he had no way of knowing. Back to 91 and all was fine again after a half tank or so.

All the Shell stations around here though have switched to some K Circle thing, so I have nowhere to get gas now... I only have about 35 miles left until empty now and still no idea where to get my gas.

 
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circle k is run by 76 so its not bad gas at least in my area...anyways well i've been doing some experimenting with gas recently...

well i found out that when i use 91 the car is definitely more peppy and quicker in response and power on freeways but my mpg goes to hell (but i do get fireballs out my muffler)...it last no where near as long as i would on 87... with 87 performance wise not as great but really great gas mileage...

i dont get as much backfire with 87 but my gas does last longer because its not dumping half of the unburnt gas out like it does with 91 (for those of you who dont know higher the octane means harder to burn) but it does burn hotter because there is not necessarily more fuel but more additive in the gas which produce more power (fuel is really complicated and im trying to describe the best i can so its easier to understand)

 
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whatever happened to s2000man01

 
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Humm... why exactly did they have the head to your car off? If they are taking the heads off, that is ALOT more work than changing your timing belt and would cost you FAR more, some thing north of the $2,000 dollar mark to have the head removed at a dealer. You don't simply have them take the head off the engine just to check for carbon, maybe they brought you a spare part or something.

 
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Actually it is Federal law that all octane dispensed from a single nozzle have the same amount of additives. If all the grades come through a single nozzle like in most stations around my place, then they all the grades at the station have the same additive content.

Octane only means the "resistance to pre-ignition." Specifically it is the ratio of iso-octane to para-octane, so 93 means it is equivalent to 93% iso-octane and 7% para octane. That being said, the higher the octane, the less prone it is to pre-ignition, it will still burn in a similar manner, at the same temperature and all that stuff. The only thing a higher amount of iso-octane (or higher octane number) will allow is for (i) higher compression, which can't happen in a civic without major modifications or (ii) advanced ignition timing, which can happen on some cars, not sure about a civic's though. I know some cars like Impreza's and SRT-4's will advance the timing if you put better gas in it, but the average car does not do this... yet.

 
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I'm sorry, I'm no mechanic, to tell you the truth i couldn't tell a cylinder head from a bicycle. I was just "acting" knowledgeable
What they did was to open the top metal part of the engine and there were rows of springs and rods, don't know exactly.I just said they looked fine to me and that's it. They charged me $60 for that.

 
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They pulled the valve cover.....

 
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ive used 91 every now and then...but usually 87 cuz im cheap...it doesnt really matter to much i dont think...that if its just a street car. you go into more issues when u need a higher detonation on certain cars or turbos...that made no sense. whatever

 
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87 octane is 87 octane. All gas is the same because it all runs through the same pipes. Now higher octane is only need if you go turbo or build your engine, other than that your wasting money, its as simple as that. Honda engineered our D17 to run off 87, so it runs best of 87.

I've always used 87 and with my 17s and my subs I can still get 38 mpg out of my car.

 
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last I heard... got married, probably had a kid...

 
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Carbon deposit in that area would mean really bad fuel or oil or both. If you're happy with 91 octane, that is fine, I'm not going to try and convince anyone that has had positive results.

 
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87 anything + fp60 = win

 
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Same here!

 
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Now that we have covered the OCTANE question. What about filling the tank to the top. I mean all the way up won't hold another drop. Is this bad?
I fill up at the same EXXON, and use the same pump, and get the same grade gas. I always fill it to the brim, that way I can get my exact mpg. Am I hurting the car by doing this?