ok so ive been using octane 91 on my car for the past 5 months now and and i own a civic ex, in which the manual says i am safe to use octane 87. but my parents told me to use the most expensive to keep the engine cleaner and stuff like that, however im running down on cash to pay for the gas, is it safe to go down a octane level without messing anything up or mixing it, ive heard that once you use a high octane level, its bad for the car to go back down. might be stupid of me to ask, but i trust you guys repsonses so thanks in advance

 

ummm nothin happens to ur engine if u run on a lower octane i would just stick with 91 but if u need to go to 89... run it rich is wat i say

 

" Octane ratings are ratings used to represent the anti-knock performance of petroleum-based fuels " you dont need to run 91 because you car has lower compression then the SI just because its 91 does not mean its going to be a cleaner fuel, that depends on alot of things i use only chevron fuel 91 octane,91 because i have a high compression engine and chevron because i was told by some one who did a test that they were one of the cleaner so now you dont need to run 91 87 is just fine

octane ratings represent the risistance to detanate

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cvicex609 &raquo;</TD></TR><TR><TD CLASS="quote">ok so ive been using octane 91 on my car for the past 5 months now and and i own a civic ex, in which the manual says i am safe to use octane 87. but my parents told me to use the most expensive to keep the engine cleaner and stuff like that, however im running down on cash to pay for the gas, is it safe to go down a octane level without messing anything up or mixing it, ive heard that once you use a high octane level, its bad for the car to go back down. might be stupid of me to ask, but i trust you guys repsonses so thanks in advance
</TD></TR></TABLE>

The only real difference between the regular and premium fuels is higher octane and some proprietary agent. These cleaning agents are often actually shared by several companies, and I don't htink you'll see much of a difference. ANyways, your car is tuned to run a lower octane, so you are either wasting the extra money or having unburned fuel in the combustion chambers because the higher octane means its a bit harder to detonate. You may not be maximizing the engine's efficiency.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by accordselux &raquo;</TD></TR><TR><TD CLASS="quote">

your car is tuned to run a lower octane, so you are either wasting the extra money or having unburned fuel in the combustion chambers because the higher octane means its a bit harder to detonate. You may not be maximizing the engine's efficiency.</TD></TR></TABLE>

 

if your parents are worried about keeping your engine clean just get a fuel system cleaner every once in a while... the only other difference with higher octane besides the detonation is most gas stations put a cleaner in the higher octane example : shell has that clean burning advertising. using there 91 and up octane your valves and injectors will stay clean... they even have a display inside the store.

hope that makes sense. i cant think or type right now.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by accordselux &raquo;</TD></TR><TR><TD CLASS="quote">
wasting the extra money or having unburned fuel in the combustion chambers because the higher octane means its a bit harder to detonate. You may not be maximizing the engine's efficiency.</TD></TR></TABLE>

so i could be losing horsepower? or even mpg by using a higher octane? should i just go straight to 87?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Cvicex609 &raquo;</TD></TR><TR><TD CLASS="quote">

so i could be losing horsepower? or even mpg by using a higher octane? should i just go straight to 87?</TD></TR></TABLE>

Technically you could be. Your power levels are probably the same, the difference is the ECU might recognize that not all fuel is detonating and increase the amount of fuel sprayed into the combustion chambers to keep it within a certain air:fuel ratio or adjusting your timing, so you may be just wasting extra gas.

The amount may be miniscule, but in the grand scheme of things, it was designed to run on 87, and it is most likely not helping very much, and may be hurting it slightly.

Lucasoil makes a great fuel additive that several people on here recommended to me that I have used for a while now. It is better off for you in the long run to just use 87 and add this to each tank to make sure you're running it clean.

I'd put the money into a fuel additive than .20c extra a gallon at the pump. It will probably be cheaper in the long run anyways.

 

to be blunt.

you're burning your money. Higher octane, higher combustion rate. Simply, you'll not burn all the fuel and be wasting it in emissions.

also, pump your fuel slowly, not fully squeezing the nozzel. it stirs fuel and the splash actually can be returned to the pump to keep from having overflow. pump in the mornings when the ground is cool and the fuel is coolest. pumping while hot gives more vapor which will be mostly lost while pumping

edit:

also, 87 and 91 octane or all transfered together. The additives are done either just prior to delivery or in some cases, on site. Only Amoco Ultimate (BP) has fuel that is never blended with lower quality fuel. If you go 91, go BP. It is by far the cleanest available for 91. Otherwise, there isn't much difference. Midgrade is a waste. its 70/30% blended of 87 and 91 respectively. That blend is done on site. Most stores now have two regular tanks and one high test tank and just blend for midgrade.

The perks of having a mother who works in the industry


Modified by drkangel650 at 12:23 AM 11/30/2007

 

Pick a name brand fuel company and stick with it. I only use chevron from the same location. If I have to get fuel from some place else I only get enough for me to make it back to chevron. Off brand fuel companies only use the minimum amount of detergent required by law in their fuels and this is reflected in the price.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drkangel650 &raquo;</TD></TR><TR><TD CLASS="quote">also, 87 and 91 octane or all transfered together. The additives are done either just prior to delivery or in some cases, on site. Only Amoco Ultimate (BP) has fuel that is never blended with lower quality fuel. If you go 91, go BP. It is by far the cleanest available for 91. Otherwise, there isn't much difference. Midgrade is a waste. its 70/30% blended of 87 and 91 respectively. That blend is done on site. Most stores now have two regular tanks and one high test tank and just blend for midgrade. </TD></TR></TABLE>

Truer words were never spoken. If Amoco ultimate is available in your area get it.

My vote: Amoco Ultimate with a bottle of chevron techron added in.

 

Just to be clear, it's onlthe the Ultimate that isn't mixed. BP's regular is shipped with other fuels just like every other

Almost forgot, never pump while a delivery is made. You risk debris and water getting into your system because all that junk settles on the bottom and gets stired when the fuel is delivered.

Hope that helps!

 

this email i was given a while back here is the old thread. https://honda-tech.com/zerothread?id=2108748 not doubting anyone just helpin yah with facts

 

BP Is defenitly the best gas going

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drkangel650 &raquo;</TD></TR><TR><TD CLASS="quote">to be blunt.

you're burning your money. Higher octane, higher combustion rate. Simply, you'll not burn all the fuel and be wasting it in emissions.


Modified by drkangel650 at 12:23 AM 11/30/2007</TD></TR></TABLE>

what are you talking about? what is higher combustion rate? octane rating has no direct impact on the burn of the air/fuel mixture in the combustion chamber. Other properties of gasoline and engine design account for the manner at which burn takes place. In other words, the flame speed of a normally ignited mixture is not directly connected to octane rating. Octane rating is a measure of detonation resistance, not burn characteristics.

 

easy example.

say 91 octane requires 15psi to burn. and 87 requires 10psi to burn.

if your car is low compression that means when the piston is traveling upwards towards the top of the block it cannot make as much compression as a high compression motor.

so on low compression car that is running 91, when piston travels to to top of the block it can only compressed the fuel to say max 10psi, therefore the extra fuel not being burn properly will be left in your cylinders, therefore overtime leaving gunk.

if you are pumping 87 in a high compression car that requires 91 octane, when piston travels about 3/4 of the way up, by this time it already made well more than 10psi, so your fuel will pre-matturely ignite, so by the time the piston actually reaches the top of the block the car is starving for fuel, hence running lean. lean cause your motor to run hotter, overtime you probably hear knocking in your motor. knocking is engine deteriorating. i guess it sounds like a can of spray paint being shaked.

all unleaded fuel will work. its the outcome that matters.
if you want to clean your engine while pumpin, i recommend using a fuel brand that claims to clean your engine, like chervon and shell claim they do. i'm in CA, those are the 2 most popular fuel in my area. other brand might do the same as well. if you want to be sure you can add in fuel injector cleaners. or you can seaform your car once in a while, this will clean yoru motor.

but my opinion, if you pump the correct fuel, your motor will be clean as a whistle. just change fluids on time and your honda should outlast your gran-children

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lv6l &raquo;</TD></TR><TR><TD CLASS="quote">easy example.

say 91 octane requires 15psi to burn. and 87 requires 10psi to burn.

if your car is low compression that means when the piston is traveling upwards towards the top of the block it cannot make as much compression as a high compression motor.

so on low compression car that is running 91, when piston travels to to top of the block it can only compressed the fuel to say max 10psi, therefore the extra fuel not being burn properly will be left in your cylinders, therefore overtime leaving gunk.

if you are pumping 87 in a high compression car that requires 91 octane, when piston travels about 3/4 of the way up, by this time it already made well more than 10psi, so your fuel will pre-matturely ignite, so by the time the piston actually reaches the top of the block the car is starving for fuel, hence running lean. lean cause your motor to run hotter, overtime you probably hear knocking in your motor. knocking is engine deteriorating. i guess it sounds like a can of spray paint being shaked.</TD></TR></TABLE>


OCTANE is not directly connected to BURN characteristics.

 

well if you want to explain the percentage of different mixture of fuel and octane go right ahead. i just post that as an easy example to understand at least some sort of how fuel works.

its very common and annoying when people keep saying they need 91 octane in new economy cars so it will run cleaner and better.

 

Just run 87 and be done with it. You don't need to use premium gas in your car. It's a waste of money.

The Si on the other hand...