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TOV Forums > Civic > > Re: 2012 Civic Si requires premium unleaded?

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CB77
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Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-14-2012 09:20
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I have a friend from the Acura Service division of American Honda. I decided to run some of our discussions on this topic by him, for a more informed opinion than mine. I list below the results, with the questions or comments in [brackets], and his responses bolded:

(And CR-V9, he gives a good answer to your question about your ECU "learning" to adjust to regular, and then not being able to re-adjust to premium, when you go back to premium)


[Another issue we encounter here at a mile high......less octane is needed as altitude rises. In fact regular in Denver is 85 octane, not the 87 seen elsewhere. I use 85 in everything without any problems. At the BMW dealership where I work part time they insist on premium in all BMWs. I am sure they could cut their costs a little by switching but not when BMW comes around to visit.]

Response: High altitude reduces the motors dynamic compression or ability to fill the cylinders so the need for high octane fuel decreases as the altitude increases.


[Ron and I have had that conversation many times he says "use cheap gas get poor mileage and power...use 91 works right" gets good mileage and power.. My TL HP uses 91.. and I get 27-28 on the road.. 20 in town]

Response: All modern motors have knock sensors and the ability to quickly adapt to any octane fuel sold in the USA. I've seen Mexican gasoline exceed the limits of some knock sensor systems, but not enough to do any permanent damage.


[Most oil industry experts that I have seen comment on this, say that new cars have their engines so well monitored and controlled by computers, that there is no problem running 87 octane in any engine. The ECU computer will quickly detect any tendency to detonate, and immediately dial-back the ignition timing accordingly. You will see a slight HP decrease and a very slight MPG decrease...but you will come out far ahead, $/wise. ]

Response: I own a 2010 Fit and a 2010 Odyssey and I run Premium in both. The Fit and the Odyssey get about 3 MPG better fuel economy with Premium which is about a 13% improvement. In LA Premium fuel costs about $.30 per gallon more than Regular so the difference in cost is only 6-7%.

[One of the participants on this website was concerned that if he tried regular for a few tankfuls, his ECU would "learn" to keep the timing retarded, even when he goes back to premium.]

Response: Not true, the ECU continuously monitors knock and adapts next cylinder accordingly

[Good question. Wish I had a good answer. I guess the way I visualize it is that the ECU computer (in an engine that is set up for premium gas) will continually try to see "what it can get away with" by trying to advance the timing as far as it can before detonation is detected. Since it was programmed to fire the spark plugs at the right time for premium gas, it will continually try to see if it can bring the timing back up to that specification. But, like I started my sentence with "I guess". ]

["Before the switch to fuel injection and computerized controls, engines were subject to damage from prolonged knocking. But today's engine management systems incorporate electronic knock sensors, which detect the condition and adjust the ignition to stop the problem. As a result, it is almost impossible to hurt a current engine by using 87-octane fuel, industry experts say. ]

Response: I agree

["Modern engines prevent the damage from happening before it starts," said Patrick Kelly, a fuels analyst with the American Petroleum Institute. "It wouldn't impact fuel economy. And it wouldn't impact the emissions. What it would impact is the performance." ]

Response: If your motor makes more torque with Premium fuel, you can make the same amount of power with a smaller throttle opening which consumes less fuel. In one of the Odyssey V6 Owner's Manuals it recommends Premium fuel when towing trailers because you can gain up to 20 HP.

[Of course, owners who do not heed the automakers' recommendations may face consequences” the potential voiding of warranties, for instance. But for the most part, manufacturers' fuel recommendations include some wiggle room. ]

Response: Years ago before knock sensors this may have been true, but modern motors are pretty smart and Honda never denied warranty coverage to any Acura owner who damaged their motor with Regular fuel because I've never heard of damage occurring.

[Porsche, for example, acknowledges that any of its modern production cars can be run on regular fuel without the risk of damage. ]

A spokesman for Porsche North America, Tony Fouladpour, added a caveat. "If you want the car to perform at its maximum capability, the best choice would not be 87," he said. "But we do not forbid it." ]

Response: Agree

[Specifying premium fuel lets a car manufacturer squeeze out more horsepower. BMW, for example, recommends that all the cars it sells in the United States use premium fuel, but they will run on regular.

"There generally isn't any harm done to the engine by using lower-octane fuel," said a BMW spokesman, Thomas Plucinsky. "Because our engines do have very good forms of knock sensing and are able to deal with lower-octane fuels, you will not have any drivability issues. You will, however, lose some of the performance." ]

Response: I've seen transmission shift quality issues caused by using Regular fuel instead of Premium. Again, with Premium you can accelerate with a smaller throttle opening. With Regular the throttle is open more which makes the transmission think it needs to deal with more torque so it shifts harder and later to compensate.

[How much of a loss? Some indication can be found in the peak horsepower numbers Hyundai recently released for its new Genesis sedan. On premium, the 4.6-liter V-8 engine is rated at 375 horsepower. On 87-octane regular, it is 368. ]

Response: This is less than Honda's 20 HP estimate, but their are a lot of variables. 7 HP may not sound like a lot, but that is about all that is needed to maintain a 60 MPH cruising speed.

[Does using lower-octane fuel reduce mileage or increase emissions, as some drivers believe? Not according to the Environmental Protection Agency. "E.P.A. fuels engineers say that there isn't a meaningful difference between regular and premium gasoline," said Dale Kemery, a spokesman for the agency. ]

Response: I agree

[Still, the warning from some automakers can give an owner pause at the pump. The manual for the Smart Fortwo repeats the warning issued for other vehicles sold by Mercedes-Benz: "To maintain the engine's durability and performance, premium unleaded gasoline must be used."

But even those stern words may have some room for interpretation. Dave Schembri, president of Smart USA, told John Schwartz, a reporter who was writing for this section's blog about his experiences in buying a Smart, that he should not worry. "You could use regular gas” there's no damage to the car," Mr. Schembri said."]
Response: This is the result of their Publications department making a statement that no one in Technical reviewed.




CR-V9
Profile for CR-V9
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-14-2012 10:17
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Thanks, CB77.

What surprised me most was this.
Response: This is less than Honda's 20 HP estimate, but their are a lot of variables. 7 HP may not sound like a lot, but that is about all that is needed to maintain a 60 MPH cruising speed.
superchg2
Profile for superchg2
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-14-2012 13:15
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Thanks CB77!
notyper
Profile for notyper
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-14-2012 13:29
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They actually get their gasoline from the same exact pipeline. Outside of 1-2% by volume addititives, you get the same gas at any gas station in your area.

I started and own what is possibly the biggest dyno tuning business in the country (in Los Angeles). In fact, I now own two, having started a second facility last year as well (Las Vegas). We tune on the order of 2000 engines/year and I am personally involved in the vast majority of those. A great deal of our business involves tuning vehicles using factory ECU systems which are then recalibrated for different parts/fuels/conditions.

Our customers include people who just want their street cars to be a little faster (or more fuel efficient sometimes) all the way up to national champion racers and record holders. Our customers have set over 2 dozen Bonneville records in 8 different classes, won multiple national championships in SCCA Solo2 and ProSolo autocrossing, won national championships in road racing at the SCCA Runoffs, the NASA Nationals, SCCA World Challenge and other lesser series. Our customers have also won championships in several Time Attack series and drag racing series. Besides the championships, our customers have many 100s (we may be getting close to 1000s now) of local and regional event wins in everything from Honda Challenge to Grand-Am.

Over the years we have worked directly with Toyota, Mitsubishi, Subaru, GM (we are the only chassis dyno I'm aware of to have dyno'd a Volt), and Honda. We also work with major aftermarket companies such as Honeywell/Garrett, AEM, Hondata, Uprev and many others you may not have heard of.

With respect to this conversation, you could say we are in the business of closely monitoring knock since that is the number one killer of engines. We use factory knock sensors, knock headphones (filtered headphones plugged into a microphone mounted to the engine), our eyes and our ears. Even on cars without knock sensors, I and my team can usually spot a knock event simply by monitoring the exhaust stream of the engine, and on all but the loudest race cars, knock is usually audible simply by listening externally to the engine on the dyno. A few as 2-3 knock events can also usually be identified by pulling the plugs and looking for evidence of aluminum deposits.

Since I am financially responsible for engines that are on my dyno (within reason - I am responsible if I screw up the calibration), I have a tremendous incentive to prevent knock. Since we also guarantee our work, I wouldn't be in business anymore if I didn't pay close attention to knock events. Knock is so important that even though my degrees are not in chemistry, I have taken it upon myself to learn the precise chemistry behind the initiation of knock in engines so as to better be able to prevent it (yes, knock, in the end is more about chemistry - ionization and the generation of radicals leading to the initiation of uncontrolled reactions).

Knock is bad, and every knock event is damaging. Just a little bit at a time, but it is cumulative and cheaping out on gas is not worth it.

SC
Jacky
Profile for Jacky
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-14-2012 13:38
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I am the originator of this thread and I thought I would share this information that I just read in the owner's manual (which I had to download since I do not actually own an Si). Under the "What to Do If" section, one of the questions is:

Q. "2.4l engine models - Is it possible to use unleaded gasoline with a Pump Octane Number (PON) of 87 or higher on this vehicle?

A. Unleaded gasoline with a PON of 91 or higher is recommended. If premium unleaded gasoline with a PON of 91 or higher is not available, you can temporarily use the gasoline with a PON of 87 or higher. This will result in decreased engine performance, and can cause occasional metallic knocking noise in the engine.


I think it is interesting that the Honda owner's manual gives the green light to at least do it temporarily without any huge problems.
DCR
Profile for DCR
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-14-2012 13:53
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Jacky wrote:
I am the originator of this thread and I thought I would share this information that I just read in the owner's manual (which I had to download since I do not actually own an Si). Under the "What to Do If" section, one of the questions is:

Q. "2.4l engine models - Is it possible to use unleaded gasoline with a Pump Octane Number (PON) of 87 or higher on this vehicle?

A. Unleaded gasoline with a PON of 91 or higher is recommended. If premium unleaded gasoline with a PON of 91 or higher is not available, you can temporarily use the gasoline with a PON of 87 or higher. This will result in decreased engine performance, and can cause occasional metallic knocking noise in the engine.


I think it is interesting that the Honda owner's manual gives the green light to at least do it temporarily without any huge problems.



It really shouldn't be all that surprising, given the scum that covers the earth.

Some moron probably pulled in to a gas station on empty with a car that REQUIRES premium, but the gas station was all out, and the only thing available was the piss water 87 octane. Much to his surprise...not only did the 87 octane nozzle fit in the tank, it actually allowed the car to start and drive down the road. Confused by this, the man assumed he'd been cheated. Later, he contacted his lawyer, proposing a lawsuit to recover every cent spent on premium over regular, plus damages from mental anguish due to the cruel joke played on him by the auto maker, who is clearly in bed with the gas companies to increase profits.

As a domino effect, high bridges have had all of their signs replaced from "DO NOT JUMP", to "DO WHAT YOU WANT - LOVE, CHARLES DARWIN".
superchg
Profile for superchg
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-14-2012 15:49
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DCR wrote:

As a domino effect, high bridges have had all of their signs replaced from "DO NOT JUMP", to "DO WHAT YOU WANT - LOVE, CHARLES DARWIN".


white06si
Profile for white06si
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-14-2012 21:52
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SC,

I didn't know you did this. How long have you been in business? What is your shops name? I owned and operated one of the best auto repair shops in Houston for 18 years. I had a great reputation with clients in major league sports, govenors, senators, federal judges, dr., attorneys, just to name a few. My business was not into tuning but just everyday repairs working on high end european and foreign vehicles. I have worked on just about everthing except a Lambo. There is a dealer here that opened a few years ago and this may change, however I have driven one. I have a very wealthy cousin in LA and he has asked me many times he wants to do mods to his vehicles, but doesn't know where to go. I will be glad to pass your name to him. By the way I did buy a set of Carbotech pads xp10 from your recommondation and can't wait till next track day in mid april to try them out.
DCR
Profile for DCR
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-14-2012 22:41
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http://www.hondatuningmagazine.com/tech/htup_0805_shawn_church_automotive_testing/index.html
notyper
Profile for notyper
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-14-2012 23:18
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Church Automotive Testing (Vegas biz is Church Dyno Testing Las Vegas). Going on 11 years now. We tune pretty much everything short of some Ferraris and Porsches.

SC
RocketRon
Profile for RocketRon
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-15-2012 09:44
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Jacky wrote:
I am the originator of this thread and I thought I would share this information that I just read in the owner's manual (which I had to download since I do not actually own an Si). Under the "What to Do If" section, one of the questions is:

Q. "2.4l engine models - Is it possible to use unleaded gasoline with a Pump Octane Number (PON) of 87 or higher on this vehicle?

A. Unleaded gasoline with a PON of 91 or higher is recommended. If premium unleaded gasoline with a PON of 91 or higher is not available, you can temporarily use the gasoline with a PON of 87 or higher. This will result in decreased engine performance, and can cause occasional metallic knocking noise in the engine.


I think it is interesting that the Honda owner's manual gives the green light to at least do it temporarily without any huge problems.



Jacky,

Did you read what SC previously wrote in this thread in regards to engine knocking? Why ask for expert advice if you're not going to believe it?

What the manual is saying is that you can use regular instead of premium in case of emergency. They should have added: During this temporary situation, drive at low RPM's AKA avoid hitting VTEC

R
A77
Profile for A77
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-15-2012 16:20
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"Response: I own a 2010 Fit and a 2010 Odyssey and I run Premium in both. The Fit and the Odyssey get about 3 MPG better fuel economy with Premium which is about a 13% improvement. In LA Premium fuel costs about $.30 per gallon more than Regular so the difference in cost is only 6-7%. "

I am no expert but I find that very hard to believe - it would also mean that premium fuel Acuras should get better mileage than similar Hondas...they don't. There are no more btus, so I find it hard to see where the extra hp/mileage comes from, without a corresponding increase in compression.

Honda manuals do say that when towing big loads and at altitude or in hot climates or for steep climbs 91 or higher octane should be used. There's no specific mention of gaining any horsepower change. (the altitude mention is contrary to the fact that altitude effectively helps octane). But anyway, all very confusing.

garoto628
Profile for garoto628
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-15-2012 21:33
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In my view, this tech lost credibility here:

Response: Years ago before knock sensors this may have been true, but modern motors are pretty smart and Honda never denied warranty coverage to any Acura owner who damaged their motor with Regular fuel because I've never heard of damage occurring.

I stopped reading at that point, sorry and no offense.
DrWhiner
Profile for DrWhiner
Re: Premium Required? Not Necessarily    (Score: 1, Normal) 04-26-2012 16:19
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CB77 wrote:
Does using lower-octane fuel reduce mileage or increase emissions, as some drivers believe? Not according to the Environmental Protection Agency. “E.P.A. fuels engineers say that there isn’t a meaningful difference between regular and premium gasoline,” said Dale Kemery, a spokesman for the agency.


Should you place total confidence in a newspaper article?

Just stumble on this.
Last year, the Cruze produced some thought-provoking results when tested on 87 and 91 octane in hot weather. Namely, on a per-mile basis it was cheaper to use 91 (the owner's manual doesn't require octane higher than 87).

LT test from IL:
2011 Chevrolet Cruze LTZ: MPG Test - Regular vs. Premium

To most of us performance equates to acceleration and speed, not mpg. After all, the sort of driving that leads to good fuel economy isn't exactly taxing one's engine. Why buy premium when you're not running hard, right?

This theory began to show cracks (for the Cruze's 1.4-liter turbo engine, at least) back in June when I drove it sedately to Phoenix at the beginning of summer in an attempt to meet or beat the EPA ratings -- and fell far short.

Instead, the hot weather led to a very noticeable lack of drive-away power and sub-par highway fuel economy. Subsequent discussions with GM powertrain bigwigs and our own Jay Kavanagh revealed that small turbo engines are especially octane sensitive, which means their computers may agressively dial back the engine calibration in order to ward off knock in high load situations or in very hot weather.

To put it another way, our Cruze LTZ might've achieved better highway mpg if I had filled it with 91-octane premium unleaded for the trip to Phoenix and back.

We decided a deeper dive was in order, so we decided to subject the Cruze to an extended hot-weather MPG test. We sent the car out into Death Valley, where it spent an entire month sipping nothing but 87-octane regular, followed by another on the "good stuff", premium unleaded rated at 91 octane.

The results are surprising.

87 octane: 4,381 miles, 179.00 gallons

24.5 mpg

91 octane: 4,551 miles, 169.73 gallons

26.8 mpg

Fuel economy during the month spent on premium fuel was up by 2.3 mpg -- a gain of nearly 10 percent. Yes, the Cruze's EPA combined rating is 28 mpg (on regular gas), but this driving pattern included extensive use of the air conditioner and much hotter weather than any EPA test dyno has ever seen. The point in this case wasn't to hit the EPA rating for the Cruze; we were interested in fuel related differences.

"So what?" you say. "Premium is more expensive."

Is it?

87 octane: $3.60 per gallon (average), $645.01 for 4,381 miles

14.72 cents per mile

91 octane: $3.82 per gallon (average), $648.74 for 4,551 miles

14.25 cents per mile

Turns out that the MPG benefit was large enough that it offset the higher per-gallon cost.

http://blogs.insideline.com/roadtests/2011/09/2011-chevrolet-cruze-ltz-the-ultimate-hot-weather-mpg-test---regular-vs-premium.html

Note: 1.4L Cruze engine is turbo charged.
Disclaimer: YMMV.
owequitit
Profile for owequitit
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 04-26-2012 16:43
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A77 wrote:
"Response: I own a 2010 Fit and a 2010 Odyssey and I run Premium in both. The Fit and the Odyssey get about 3 MPG better fuel economy with Premium which is about a 13% improvement. In LA Premium fuel costs about $.30 per gallon more than Regular so the difference in cost is only 6-7%. "

I am no expert but I find that very hard to believe - it would also mean that premium fuel Acuras should get better mileage than similar Hondas...they don't. There are no more btus, so I find it hard to see where the extra hp/mileage comes from, without a corresponding increase in compression.

Honda manuals do say that when towing big loads and at altitude or in hot climates or for steep climbs 91 or higher octane should be used. There's no specific mention of gaining any horsepower change. (the altitude mention is contrary to the fact that altitude effectively helps octane). But anyway, all very confusing.




There are a lot of factors at play A77, but realistically, Acura's running premium typically get MPG performance close to their regular tuned Honda counterparts. For instance, the 3rd gen TL with a J32 returns similar MPG performance to the Accord V6, despite having more displacement, torque and power in a car that is slightly heavier.

I can also vouch for the performance of some Honda cars on premium, such as the aforementioned Accord V6s. In the case of BOTH of our 7th gen EX-L V6's MPG goes up by about 2-3MPG on average when running premium. The disclaimer is that it usually take a full tank or two of premium to see the full result. My guess is that is the ECU learning period. The reason is already mentioned by Shawn. Typically, you get better power delivery and more area under the curve due to the increased knock resistance of the better fuel, and the ECU's ability to dial in timing as a result. With the extra area under the curve (where a few HP or lb-ft can be pretty significant at part throttle load) you spend less time accelerating and more time in cruise. You also have to run the engine at lower loads to get it to accelerate, all of which contribute to MPG. I can also say that in the case of both of our 7th gen EXL V6's, not only did MPG improve noticably, but the engines are measurably more responsive and feel slightly more powerful than when running on 87 octane. If you can actually discern the difference, then you are dealing with a gain in power that is not insignificant.

Finally, it must also be considered that it is predicated on the ECU's abilities to adjust. The 7th gen V6 was able to adjust pretty substantially for ignition timing based on fuel quality, and that is shown in dyno results. The 8th gen, on the other hand, doesn't really compensate for better fuel, which is also shown on dyno charts. Thus, in a car like the 7th gen, it makes sense to run premium. In a car like the 8th gen it does not.
P54
Profile for P54
Re: Premium Required? Not Necessarily    (Score: 1, Normal) 04-26-2012 16:45
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87 octane have 10% ethanol while premium do not contain ethanol, at least that is what local gas station owner told me. Ethanol in gasoline cause less mpg. By that alone it is easy to see that running premium will give you better mpg. Different engines can benefit differently, some designs will benefit more than others from using premium instead of 87. Using premium also improves the performance of small engine equipment. Ethanol fuel cause lots of problems for boat engines as well. Using ethanol fuel on such equipment, and two strokes as well, can cause lots of problems. Use fuel stabilizers like Sta-Bil or Star Tron.
internalaudit
Profile for internalaudit
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-24-2013 23:57
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Maybe I've got no right to post since I don't own an SI but we do have a 2011 Honda Accord EX-L coupe that should have a similar engine.

The compression ratio only .5 higher on the SI. The recommended fuel for our Accord is regular. Did the previous generation of SI's have much higher compression ratio that 11:1?

K24Z7

Found in:
2012 Honda Civic Si (US)
Displacement: 2,354 cc (143.6 cu in)
Bore and Stroke: 87 mm x 99 mm (3.43 x 3.90 inches)
Compression: 11.0:1
Power: 201 HP @ 7000 rpm
Torque: 170 lbs·ft @ 4400 rpm
Redline: 7000 rpm
Fuel Cutoff: 7200 rpm


K24Z3

Found in:
2008+ Honda Accord LX-S/EX/EX-L trim models (CP2, CS1)
Displacement: 2,354 cc (143.6 cu in)
Bore and Stroke: 87 mm x 99 mm (3.43 x 3.90 inches)
Compression: 10.5:1
Power: 190 hp @ 7000 rpm
Torque: 162 lb·ft @ 4400 rpm
Redline: 7100 rpm


ClementZ
Profile for ClementZ
Re: 2012 Civic Si requires premium unleaded?    (Score: 1, Normal) 03-25-2013 02:25
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Interesting.

My father and I always refrained from filling up with premium and up octane ratings because of the extra cost, but it seems that higher octanes (in most cases) definitively improve both power and fuel economy.
The Accord (2005 LX 5MT) that we share (I haven't my own car because $400/month insurance) has 292 000 kms on it (181440 miles). And all this time, it has run on regular unleaded.
Would anything...bad happen to it if we suddenly switched to premium or midgrade?
And would it be worth it?
Regular is currently $1.29 a litre here (roughly 4.89 a gallon) and Premium is currently $1.46 a litre (roughly 5.52 a gallon).
 
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