cdero

Ok, I've read some threads about this and there seems to be no clear answers. My car manual suggest to simply use regular but others think differently. Is paying more for a higher octane improve gas milage, engine, etc, or is it just a waste of money? And, what about natural pure gas?

BLKFLSH

The people at consumer reports had an interesting comment on this. "Buying higher octane gas (93) for a car that requires less (87), is like buying a size 13 shoe when you wear a size 10. Sure, you're getting more shoe, but if it doesn't fit, it's a waste of material." The higher octane is also a waste IMO. My engine still purrs like a kitten after more than 10 years, and 113k miles, on plain old 87 octane. As long as you use a good detergent gas, you don't even need the bottles of so called injector/fuel system cleaners.

cdero

Ok, so is there a way to determine what gas has good detergent in it?


Also, what's the deal with pure ethanol free gas?

BLKFLSH

There is what Honda, and others call "top tier" gas. Google it, to get all the brands, but they are the brands recommended by these car companies. There is a local station (Conoco) that sells ethanol free gas, which most people say is better. I tried it, and actually found my engine didn't run as good on it. It seems to me that the engine runs better on the Texaco gas I've always used, which has 10% ethanol. Maybe I didn't use the Conoco long enough for my engine to get accustomed to it. My car runs just fine on the Texaco/Chevron (with techron), and I can easily find it when I'm out of town, whereas Conoco doesn't seem to be as easy to find. That's why I decided to just stick with the Texaco/Chevron, even if it does contain ethanol.

MSchu

if you had the v6 I would have an argument about "not using" high oct petrol... but with the four cylinder, blacky has the correct answer.

BLKFLSH

I've heard the thing about higher octane adding 10hp to the V6 engine. Considering the extra cost, and the instances when I would actually use that extra 10hp, I don't feel like it's worth it. Not that I actually believe it is true in the first place.

Bakemono36

I think to properly have this discussion, we need to make sure that we all understand what octane rating is and why its important. So, octane rating refers to the fuel's ability resist detonation. If the rating is too low, the fuel ignites from the pressure of compression before the piston reaches top dead center and you lose power, as well as putting a lot of stress on the engine.
The engine is designed to run on 87, you gain NOTHING with 89 or 93.
Now, if you had a V6, it would be worth it to run 93 because that is a higher performance engine that has a higher compression ratio, so it needs 93. It is true that you can run 87 in it if you have to because the computer will sense detonation and will retard the timing to compensate for it but its really not worth risking damage to the engine just to save 30 cents a gallon.

BLKFLSH

Engine damage, from using 87 octane? I've never heard that before. What would be the evidence of this?

Bakemono36

If its designed for 93, youre going to get some level of detonation even with knock sensors adjusting the ignition timing to compensate for it.
If it didnt matter, they would specifically say in the owner's manual to use 93. Those warnings are in the manual to protect the manufacturer from warranty claims due to operator ignorance.
It would be one thing if you had a manual setting where you could set it to the timing curve for 87 or 93 octane fuel but when the computer does it all, the default setting is for 93, so you cant really protect the engine as much.
For example, I used to have a snowmobile with an engine that was designed to run on 93 but it had a manual switch where you could set it to either, "regular" or, "premium". It was there for the instance where you either couldnt find 93 or were unsure of the quality of the fuel to protect the engine from damage due to detonation.

1998GsRIntegra

Nailed it for the most part

DCFIVER

I have an RSX type S. It requires 91 octane, minimum. Based on a discussion in another forum,I ran 87 octane, for testing purposes. My gas mileage went down by 5mpg and my scan tool recorded 60 knock events through one whole tank of gas. Returning to 91 yielded a return to normal gas mileage(approx 300 miles per tank) and 0 knock events recorded.



I did not feel any of the knock events, nor did I notice when the PCM pulled timing. However they obviously were present, and this type of activity over the long term will destroy the piston tops and valves.....

BLKFLSH

This engine(J30) is not designed for 93 octane, and 93 is not the default setting . It's designed for 87. The owner's manual actually says 86 or higher.

BLKFLSH

This is not an Acura, and it doesn't require 91 octane. The owner's manual says 86.

DCFIVER

LoL. Reading comprehension problems???


Make and model of the vehicle is meaningless to this discussion,it was only used as an example. I suggest you reread the thread....slowly.

DCFIVER

He never said it was....

BLKFLSH

This discussion is about 7th gen Honda Accord engines, and neither of them require 93 octane. So why are we talking about Acura engines? I don't care what octane Acura engines require. If you ran 87 octane in your Acura, you are the one with comprehension problems. It requires higher octane.

94vtecmn

Um

This sounds like he actually did say it was.

At any rate, the J30 does not have a high enough compression ratio to require "Premium". I'm sure there are other V6's that do, heck, there are I4's that require "Premuim" because they have a higher compression ratio.

In this case, the 7th gen Accords do NOT require "Premium", V6 or I4.