So who is using regular gas in these cars?

Byron Sexton

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I just read somewhere that these cars can take regular gas, Honda recommends premium though. What performance wise could happen in using regular vs Premium gas? Are there tested viscosity tests? Facts that show regular wear vs premium wear on the gas lines? I'm curious. If this has been asked before feel free to point me in the right direction.
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18TypeR-13922

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I just read somewhere that these cars can take regular gas, Honda recommends premium though. What performance wise could happen in using regular vs Premium gas? Are there tested viscosity tests? Facts that show regular wear vs premium wear on the gas lines? I'm curious. If this has been asked before feel free to point me in the right direction.
I'd bet not many people except in a emergency where premium was not available. Like most other cars that require premium, performance will be degraded by the computer.
 

Galaxythief

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I'd imagine ECU would pull timing and the car would perform worse. No proof of this though.
 

stevessvt

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With how low the price of gas is right now, premium is now the same price as regular a few weeks ago. There’s no reason to put regular in right now other than an emergency.
 


Jwolf

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These cars excluding the Si and CTR are engineered to run on 87 octane. As long as you buy from a reputable gas station you will have no issues. There is no “but premium fuel is cleaner” it’s all the same just different levels of additives to increase octane. There is no “premium fuel leaves less gunk in the engine” it’s a direct injection the valves will get gunked up regardless and that’s not lower octane fuels fault that’s the PCV valve’s fault. You want a cleaner car run an oil catch can. Yes you will get a slight boost in mileage but we’re talking minimal (depending on your driving habits) maybe 1-15miles extra a tank at best. Yes the rated hp on these vehicles was achieved on high octane fuel, but you won’t even see those hp numbers unless you are full throttle at red line lol. There is so much misconceptions with fuel it’s pretty funny lol. The point of the octane rating is to scale the gasoline to tell you how resistive the gas is to pre-ignition and knock. As long as the fuel is at least 87 unleaded and it’s not a Si, a Civic Type R, or a tuned vehicle the car can use 87. Of course it’s your vehicle and you can put what you want into it, but from the dealer the tank the dealership fills up is 87. I ran 91 because I was tuned, but now I run a 91+E85 blend
This is the Type R section.
 

NoelPR

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I got the perfect answer.

Don't get the CTR or the SI if you are considering using regular gas on them.

I guess that your next question will be if you can use base civic tires because the CTR ones are so expensive.
 

yargk

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I just read somewhere that these cars can take regular gas, Honda recommends premium though. What performance wise could happen in using regular vs Premium gas? Are there tested viscosity tests? Facts that show regular wear vs premium wear on the gas lines? I'm curious. If this has been asked before feel free to point me in the right direction.
The car wasn't designed for regular gas so you'll get less horsepower and the car will be less responsive. You could also get worse gas mileage, which would undo any cost savings. Please don't use regular gas in this car. Think about it this way: if you drive 10,000 miles a year, you're only going to save about $100 a year using regular gas vs. premium. Why did you spend over $35,000 on the car if you can't afford just $100 a year to have it perform how it should?

There are many ways to save way more than $100 a year: change your cable tv plan, refinance any loans you might have, insulate your place of living better, get a credit car with a better rewards program... ;)
 

yargk

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OP you'll regret making this topic. I've tried to make topics like this, and it just turns into a pissing contest on who uses the most premium premium with literally zero answers from anyone who has run the car on anything less than unicorn cum.

Meanwhile, you'll get a zillion answers like the above, restating the content of the "Fuel" section of the manual, ad nauseum.
Language please...

Anyway, within the polite suggestions above, people did answer the question by saying that you will get decreased performance with regular (87 or 89) gas. Do you want more details of exactly how much less power? Why don't you hook up a datalogger and record pulled timing? Even a VW 1.8 TSI that's supposed to run on 87 will pull timing more going up a hill than with 91. You can go dyno with 87 and 91. That would be very interesting data to see.

If you're not happy with the generally correct answers above, why don't you do your own quantitative testing and share? I'm not being sarcastic and would be eager to see the results.
 


yargk

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while I see that you successfully petitioned to have my post removed,
1. Obviously it wasn't me, because I quoted your post.
2. Saying "language please" is a friendly jab and not being an "arbiter"

Better luck next time on those powers of deduction and reading comprehension, respectively.
 

EdG

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I know the CTR computer changes engine performance based upon the octane level of fuel used, but how does it know? Is it engine performance, i.e. power produced or how the fuel is burnt via oxygen sensors? Is there a fuel sensor that can measure octane? Just curious. Looking for real info (mechanics or engineers out there) and not speculation.
 

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It’s funny on how words change when I was younger from 1975 ( when unleaded started) to the early to mid eighties ( at least in New York) regular gas would be known as leaded. I remembered when my parents would get gas the Gas station attendant ( remember them) would ask regular or unleaded. Today regular is known as 87 octane
Just my 2 cents :)
 

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I know the CTR computer changes engine performance based upon the octane level of fuel used, but how does it know? Is it engine performance, i.e. power produced or how the fuel is burnt via oxygen sensors? Is there a fuel sensor that can measure octane? Just curious. Looking for real info (mechanics or engineers out there) and not speculation.
This is where the knock sensor comes into play. If the ECU sees knock, it will reduce timing. This decreases power output, and allows you to run lower quality fuel safer. The ECU will not make any changes until it does see knock, and it will always be looking for an opportunity to increase ignition timing back to normal levels. This logic is in place in case you accidentally get a bad tank of fuel, or in emergency situations. It should not be relied upon for every fill up.
 
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remc86007

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I would never run regular in my CTR as I would be terrified of the risk of damage from knock at 20+ PSI occurring before timing is pulled. However, I also would bet that if you put regular in it and never entered boost (perhaps on a long highway trip or something) you would likely see exactly the same MPG. Maybe someone can prove me wrong, but I don't believe that the engine is running at the limits of high octane timing when cruising and therefore I don't think any efficiency is gained by the extra octane, or whatever advantage is there is likely offset by the displaced energy density.
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