Sup guys...im new here and a quick search didnt get what I was looking for so I figured I might as well ask.

How many of you guys use premium or 91 octane to fill up your Fit?

Just got me a Fit about 3 weeks ago and i read thru the manual that it was designed for 87 and higher but the thing that got me was "use of lower octane can cause a persistent, heavy metallic rapping noise that can lead to engine damage."

Advice/Comments?

 

You will get the best milage running 87 octane fuel.

 

i dont know i just pour 91. yeah people say its useless. but i know it burns cleaner, and for no more then 3 bucks a tank extra i dont mind.

and i actually do feel a slight difference. it doesnt feel like its so sluggish when i pour 91.

 

[quote=ImOnJuryDuty;275778]Sup guys...im new here and a quick search didnt get what I was looking for so I figured I might as well ask.

How many of you guys use premium or 91 octane to fill up your Fit?

Just got me a Fit about 3 weeks ago and i read thru the manual that it was designed for 87 and higher but the thing that got me was "use of lower octane can cause a persistent, heavy metallic rapping noise that can lead to engine damage."

The Fit is cesigned to use octane 87 gasoline. Use of gas with octane less than 87 will increase your likelyhood of getting carbon deposits, especially on the upper side of valves.
You may get better gas mileage on 91 (west coast) or 93 (east coast) because the recipes for higher octance often accompany gasolines with higher energy levels; the more bTu per lb of fuel the more likely to go farther on less consumption. (its not a big deal unless you're going on track.

 

Higher octane fuels allow a higher compression ratio. Additional energy in the fuel, if there, is a secondary effect. For the primary purpose, using a higher octane fuel in a lower octane engine is useless. There may be other reasons though - some of the gas companies claim they use better additives in the more expensive fuels. Not sure if that's just marketing or fact but additives do make a difference in preventing carbon deposits.

RG

 

There are alot of older posts on octane that are pretty good reads if you look around a bit but the car was designed for 87. Anything above is personall opinon.

 

Honestly, I started off with 91 octane when I bought the car. Then because I read the forums here on the subject, I let the tank get to empty and filled it with 87. I notice no difference in performance, and it is cheaper. No pinging sounds, no lag or sluggishness. I think the car is designed for 87, and it does fine with that. Truly a matter of taste and perhaps driving style, but you're fine down to 87 and so is the car.

 

[quote=Rob22315;275915]Higher octane fuels allow a higher compression ratio. Additional energy in the fuel, if there, is a secondary effect. For the primary purpose, using a higher octane fuel in a lower octane engine is useless. There may be other reasons though - some of the gas companies claim they use better additives in the more expensive fuels. Not sure if that's just marketing or fact but additives do make a difference in preventing carbon deposits.

While higher octane indicates more resistance to knocking (pinging) parts of the recipe components for higher octance involves components such as toluene that offer as much as 5% more bTu per pound of gas, which is why you may - but not guaranteed to - get better mileage. And we have seen on many occasions switching from regular to high test almost always yields higher top speed runs. Part of that is attributed to first more energy available and second often allows more ignition advance.
And yes it used to be that premium gas got better additives or at least a bigger dose. Its been a while since I ran a refinery so I can't say that's still the case. The others still hold though.
With current demands on gasoline availability there is considerable efforts to address all of these things.

 

use 87 octane

 

Guess you missed the grandfather of octane posts during your perusing the old posts. Any and all octane question and everybody's opinions are in there.

https://www.fitfreak.net/forums/fit-...1-93-95-a.html

 

Damn, the amount of misinformation in this thread is unbelievable. For god's sake, check Google, Wikipedia, or the other 2 million threads on other forums about this exact topic.

Quick summary: If your car is made to run 87, run 87...you'll get better mileage and more power.

Also, higher octanes are not 'more powerful', nor do they 'burn cleaner'. Follow the above instruction to learn why.

 

Read your manual.

87 Octane. Costs less. Works best.

After you add your supercharger then you can use Premium fuel.

 

You need to check the American Petrolueum Institute, AIChE, and ASME rather than Wiki and Gooble. Their references are not very authoritative in matters political nor in technical issues. For example: those college professors who claim there is no advantange to synthetic oils are in opposition to all of us with dynos who measure the gains in power, lesser fuel consumption, and reliability with synthetics. Political correctness overloaded.

While premium fuels are not always 'more powerful' ( higher energy content per pound) they are nearly always so because of the recipes that yield higher octane. Those that aren't are mostly getting higher octane with additives that are more costly and not always as environmentally nice as usual petroleum components. Using some of those compounds F1 gasoline some years ago produced as much as 145 bTu per pound but required full chemical protection of their pit fuelers to protect against their toxity. Fi wisely outlawed such. But in racing if you don't get caught you didn't cheat.
Gasoline is a combination of dozens of organic compounds derived from widely variable crude oil. Refinerys pick and choose the ones they can best use to yield standard and premium gasolines. The recipe can differ daily, even hourly, depending on the feedstock. To think there is little difference in regular and premium energy content is misunderstanding the chemical processing occurring in a refinery. And what it takes to produce billions of gasoline and diesel for our vehicles. Course, you might try explaining why east coast premium is 93 octane and west coast 91. And why aviation gasoline at airports and race gas at the track exist.

The issue of using 87 octane is indeed pretty straight forward. Saving money means using 87 octane; reserve premium to those cars that require it or for services that work the engine harder. Mountain hauls, trailer towing,etc. Your vehicle will thank you for it.

PS there is a rumor going around among engineers that in order to maximixe gasoline production there has been a decline in energy content (not much just a couple of percent) for regular grades of fuel. Anybody see a decline in their gas mileage? Curiosity.

 

the quick and the short is higher octane is to prevent detonation inside the cylinders on a high compression or higher horsepower car.

Higher octane "supposedly" has more additives to help clean the engine as you drive.

I have seen tons and tons of hondas go with 87 octane for 200 000 miles with no issues as long as proper maintenance is done.

This is not a performance engine and the ecu will not give you more power if you use better fuel so why not stick with 87 octane and save a few bucks.

If you want to make sure the engine stays clean maybe run some 91 octane 5-6 times a year and all should be good!

 

I'd just run the 87 octane as recommended by the manufacturer unless you are going FI. My uncle actually went up to premium from his recommended regular unleaded fuel and developed an engine knock after 1 year of the higher octane fuel. The engine was designed for 87 octane, so use 87 octane!

 

Hmmmm I'm gonna have to ask around about your last paragraph, it intrigues me I'm on the upstream side of things so I see the crude from the ground and then ship what we produce to the refineries so I can't comment on that end of the O&G business. It does seem feasible though, refining crude into gasoline takes up a lot of energy and by reducing the energy content in the fuel, it will reduce the amount of energy spent to refine the crude into gasoline. It'll have a minor effect in your gas mileage overall, but save a lot of energy spent by refineries. I doubt you will notice the difference caused by this slight decrease due to the human factor while driving and no specific shipment dates to compare results under a controlled environment.

 

lol, why does this topic keep showing up every couple of months

USE THE RECCOMENDED OCTANE
Please use as directed and take with a grain of salt!

 

I agree. Higher octane prevents detonation...is this the reason why I feel a lag when RPM is under 3K using 91 gas? Heheh, but I feel a slight biger Vtec effect with 91...it's really weird to me. I still wonder if 91 gas will burn completly on lower RPM since it resist detonation. I heard the fit is suppose to have a knock sensor. What's the use of using higher octane gas if the sensor suppose to prevent knocking? Also, for additive, I'm just going to do gas treatment before every oil change. So it's gonna cost me about $15-20 per 100+ gallons? which is less than 20 cents a gallon...hmmm...

 

_ Ethanol? _

 

Good point. I doubt there's much processing energy savings but the yield of gasolone from a barrel is rumored to be higher. Right now I suspect its not the cost thats first priority but the yield. Getting 22 gal instead of 21.5 would be a large return on investment.