ive had my fit for about 9mnths now and ive been running on 91 octane gas. if i suddenly switch over to 95octane will it have any negative side-effects on my engine? is it ok to switch back and forth? input would be greatly appreciated. thanx

 

Your owner's manual should tell you the minimum octane rating. There are two schools of thought on this subject.

1. Just use the minimum octane rating your owner's manual specifies. Anything more, and you are wasting money.

2. Higher octane boosts performance and mileage.

I have built a simple spreadsheet I will have in my PDA for when I get my Fit. When I fill up, I will enter the mileage, amount, and cost of the gas. It will then tell me mileage and fuel cost per mile. I will use that info, along with input from the buttometer, to decide which is best. Right now, it is set for $ and gallons, but changing the column headings to Baht and liters would be easy. If you would like it, PM me with your email, and I will send it to you.

 

Higher octane ratings will not benefit you at all.

'Octane ratings' are an abstract of how a specific gasoline resists 'detonation', or the tendency to spontaneously ignite when compressed. Octane is a stable hydrocarbon that is very resistant to detonation, whereas Heptane is very unstable, and will detonate easily. The octane rating of gasoline is the resistance to detonation in a ratio as if the gasoline were purely heptane and octane mixed.

You do not need to, nor do you benefit from running higher octane in a car that does not require it.

Engines with higher compression ratios, and those with forced induction, require higher octane to reduce 'pinging', which is when gasoline ignites prematurely in the combustion chamber.

Go by what your manual says. If it says 87 octane, then you do not need to run anything more. You will NOT benefit from it.

Some also speculate that higher octane gas in an engine that does not require it will operate at a lower temperature, and may not completely burn the fuel introduced into the cylinder. So running higher octane is actually BAD.

 

hey dude, mine is running with 98octane, the more octane u use, the more power u get from ur fit and the cleaner the engine is down the track, but it cost a bit more for higher octane petrol. it's worth it!!

 

anything above the recommended octane is a waste. unless you have a turbo or supercharged engine it's pointless.

 

In agreement with what everyone else is saying, I have to say that this is probably wrong. A car's fuel mapping has to be able to take into account higher octane, but the fit's fuel mapping is only designed for 87. Any more, and you truly are wasting money.
A good example of this in real life would be from my previous car, stage 2 05 WRX. It takes 91 octane, and if you put in any more, nothing really changes. Later on, I got a chip with which you can re-flash the ECU to change the fuel maps. One time I got about a 3/4 tank of 100 octane gas, and i changed the fuel map to 93 octane to take advantage of the boost, and yes it did change things quite drastically, but without that fuel map change, it didn't really do jack.
As for the comment on keeping the engine cleaner, I disagree with that as well. I have an engineer friend who works at Chevron that has taught me what I know about this subject. Some gasolines come with detergent additivies, such as Chevron's "Techron". Techron is available in all of their octane ratings, thus all of the octane ratings "clean" just as well as any other. The reason gasses like Arco are so cheap is because they don't use additives or they don't use as much, I forgot.
Some will argue that Techron is marketing BS, but I believe my friend that works at Chevron..she's a chemical engineer, so I trust her word.

Hope this sheds some light on the issue.
Tre

 

My thinking on "additives" is that they take up fluid space where "fuel" could be. I'm assuming the additive isn't fuel itself. So it seems like a great way to get less gas for your money is to get one with additives in it.

 

higher octane fuel burns slower, hence its resistance to detonation. Putting it in a car that was designed to run on a fuel with a much lower octane rating will not benefit you or your car in any way.

 

Actually, I'd say, run 95. I will continue to run 87. In 5 years, lets see who has more engine problems. We don't need to trust the facts, lets just test it.

 

use 87 octane. by using anything above 87 is only wasting your money and damaging your motor, it doesnt benefit you in anyway; it doesnt make your car stronger or faster but worse.

 

Waste of money going with a higher octane if the engine doesn't require it.

 

From what my chemistry professor told us years ago was that the RM/2 method of caculating octane was at best an educated guess. That was 20 yrs ago so mabye that has changed since. Has it gotten to be more of a science??

 

Keep kidding yourself. Your wasting your money. 87 octane is all you need. If you want to donate money to the Oil Companies, go ahead.

 

One reason that higher octane fuel could give you improved performance is this: modern engines use "knock sensing" technology, where the ECU detects pinging and retards the ignition timing to stop it. Higher octane fuel will result in less pinging, or pinging only at much higher rpms, meaning that your ignition timing stays in the performance range longer.

But as for any damage, no. And I don't think that anyone is going to see a big performance boost from higher octane fuel in a 109hp vtec 1.5.

 

If you feel the higher octain rating will save repairs, use 87 and bank the difference for repairs, you could save $1.00 a week thats maby $52 per year and $250 in 5 years or 60,000 miles when its out of warrenty.

Everything I have read says use what the manufacture recommends.

 

Here in LV we have the following grades: 87, 89, 91. Usually I use 89. Do I normally notice a power difference during daily driving no. However going between here and LA, yes. Why? Because of the altitude differences along the way. I know this is a bit much but I hope it gets the point across. This is from LV to Alta Loma, CA using I-15:

LV, NV - 1998
Primm, NV - 2621 ft
Jean, NV - 2841 ft
Halloran Summit - 4,000 ft
Halloran Springs, CA - 3,002 ft
Baker, CA - 935
Bartsow, CA - 2,169 ft
Victorville, CA - 2,723 ft
Cajon Pass, CA - 4,190 ft
Alta Loma, CA - 1,371 ft

And actually between Baker and Barstow there is another pretty large pass in there as well. On that drive the better Octane seems to perform better. I can only guess that the detonation in the lower ocatane is causing the engine to run differently. Who knows. Pretty much people when it comes to your Octane run what you want to run. Deciding which is better is like asking what the best color is, or which is better Chevy or Ford.

 

Me with a L13A IDSI :


with 95 = 7liter/100km gas millage
with 98 = 6.3liter/100km gas millage (one time with 4 people in the car and other things, same gas millage)


The IDSI burn more fuel in Higway. I think with a Mugen filter, i can increase gase millage.

 

So, you are getting 10% better mileage with the higher rated gas. If 98 is less than 10% more, in your case, it would make sense to use it.

 

cool someone in switzerland as well, im getting
7liter/100km on 95 octane also

 

I used to drive my 99 accord 4 cylinder around with a OBD2 screen permanantly attached.

when i use 87 octane (as recommended), the timing advance is LOWER than if i used 92 octane

so in contrary to what was said here, the stock computer does compensate for the knocking in the engine and DOES in fact retard timing

what's minimum is going to get the car moving, but we are performance oriented, so minimum is never good enough :-)

-joe