Honda Car Forum

Hello!

I recently bought a Honda Civic Hybrid 2005 and its User Manual says
that "Gasoline Grade should be 86 or higher", which means any grade
above 86 which could be "Regular 87", or "Mid-Grade 89" or even
"Premium 93" can be used, as I understand. If I use "93 Grade
Gasoline", will it do any harm to the engine? What are the pluses and
minuses in using the "93 Grade"? What would you recommend and why?

I thank you for your time and will appreciate your advise.

Regards,
SG

SG wrote:

> Hello!
>
> I recently bought a Honda Civic Hybrid 2005 and its User Manual says
> that "Gasoline Grade should be 86 or higher", which means any grade
> above 86 which could be "Regular 87", or "Mid-Grade 89" or even
> "Premium 93" can be used, as I understand. If I use "93 Grade
> Gasoline", will it do any harm to the engine? What are the pluses and
> minuses in using the "93 Grade"? What would you recommend and why?
>
> I thank you for your time and will appreciate your advise.
>
> Regards,
> SG

Just use the "Regular 87". Using higher octanes won't harm the engine, but
it will definitely harm your wallet.

In article <1119750302.303680.110150@g43g2000cwa.googlegroups .com>,
"SG" <Shur007@gmail.com> wrote:

> Hello!
>
> I recently bought a Honda Civic Hybrid 2005 and its User Manual says
> that "Gasoline Grade should be 86 or higher", which means any grade
> above 86 which could be "Regular 87", or "Mid-Grade 89" or even
> "Premium 93" can be used, as I understand. If I use "93 Grade
> Gasoline", will it do any harm to the engine? What are the pluses and
> minuses in using the "93 Grade"? What would you recommend and why?
>
> I thank you for your time and will appreciate your advise.
>
> Regards,
> SG

They'll all run the same so go for the lowest octane from a station that
sells fresh and clean gasoline.

Older cars are more sensitive to the octane rating. Their
air-fuel/emissions systems are operated by mechanical vacuum controlled
valves that are out of adjustment without sea-level air pressure behind
them. You had to reduce the octane at high altitudes to compensate for
the extra EGR and retarded ignition timing.

Newer cars use several feedback systems so that the engine runs at its
best under a wide range of conditions.

In article <1jfl1zo9zf0s1.dlg@ss.me-privacy-net.com>,
"S.S." <me@privacy.net> wrote:

> Just use the "Regular 87". Using higher octanes won't harm the engine, but
> it will definitely harm your wallet.

Higher octane fuel, in fact, will lead to *less* gas mileage for that
car.

Elmo P. Shagnasty wrote:
> In article <1jfl1zo9zf0s1.dlg@ss.me-privacy-net.com>,
> "S.S." <me@privacy.net> wrote:
>
>
>>Just use the "Regular 87". Using higher octanes won't harm the engine, but
>>it will definitely harm your wallet.
>
>
> Higher octane fuel, in fact, will lead to *less* gas mileage for that
> car.
>
not necessarily. depends how smart the engine management system is. in
the "old" days before knock sensors and crank angular velocity
measurement, igniton timing had a fixed map. with the above sensors,
you have a base map, but also an algorithm that monitors these two other
factors and from that, it can calculate in real time a set of new
ignition characteristics to take maximum advantage of any particular
fuel. i would hope that the expensive "super econo" car's management
would be this smart.

In article <i_WdnbHfUslmVCPfRVn-jA@speakeasy.net>,
jim beam <nospam@example.net> wrote:

> > Higher octane fuel, in fact, will lead to *less* gas mileage for that
> > car.
> >
> not necessarily. depends how smart the engine management system is. in
> the "old" days before knock sensors and crank angular velocity
> measurement, igniton timing had a fixed map. with the above sensors,
> you have a base map, but also an algorithm that monitors these two other
> factors and from that, it can calculate in real time a set of new
> ignition characteristics to take maximum advantage of any particular
> fuel. i would hope that the expensive "super econo" car's management
> would be this smart.

No, it has no need to do any such thing. It is designed to operate on
86 octane fuel. It has no need to "take advantage" of anything else.

Elmo P. Shagnasty wrote:
> In article <i_WdnbHfUslmVCPfRVn-jA@speakeasy.net>,
> jim beam <nospam@example.net> wrote:
>
>
>>>Higher octane fuel, in fact, will lead to *less* gas mileage for that
>>>car.
>>>
>>
>>not necessarily. depends how smart the engine management system is. in
>>the "old" days before knock sensors and crank angular velocity
>>measurement, igniton timing had a fixed map. with the above sensors,
>>you have a base map, but also an algorithm that monitors these two other
>>factors and from that, it can calculate in real time a set of new
>>ignition characteristics to take maximum advantage of any particular
>>fuel. i would hope that the expensive "super econo" car's management
>>would be this smart.
>
>
> No, it has no need to do any such thing. It is designed to operate on
> 86 octane fuel. It has no need to "take advantage" of anything else.
>
but formulations change between producer, by country, by state, by
season, by law, by mistake... there's plenty of reason to use smart
management, and a by-product of that is being able to run any grade gas
to best advantage.

In article <X6CdndVcWtBDRSPfRVn-3Q@speakeasy.net>,
jim beam <nospam@example.net> wrote:

> but formulations change between producer, by country, by state, by
> season, by law, by mistake... there's plenty of reason to use smart
> management, and a by-product of that is being able to run any grade gas
> to best advantage.

no, the *only* thing it has to do is prevent engine damage from knocking.

You don't program it to run any grade at that grade's best advantage.
For example, where does that stop? Can I put avgas into my Hybrid and
the programming will "take advantage" of that?

It's designed to run at 86 octane. Yes, the engine management computer
will prevent damage should lower octane fuel be present, but that's
different from saying it will change the engine parameters for more
performance if higher octane is present.

It doesn't do that.

Elmo P. Shagnasty wrote:

> In article <1jfl1zo9zf0s1.dlg@ss.me-privacy-net.com>,
> "S.S." <me@privacy.net> wrote:
>
>>Just use the "Regular 87". Using higher octanes won't harm the engine, but
>>it will definitely harm your wallet.
>
> Higher octane fuel, in fact, will lead to *less* gas mileage for that
> car.

IIRC the V6's will do better on premium petrol. They include sensors to
notice the reduced tendency to knock & will optimize timing to take
advantage of it. (been discussed previously on this NG)

Elmo P. Shagnasty wrote:
> In article <X6CdndVcWtBDRSPfRVn-3Q@speakeasy.net>,
> jim beam <nospam@example.net> wrote:
>
>
>>but formulations change between producer, by country, by state, by
>>season, by law, by mistake... there's plenty of reason to use smart
>>management, and a by-product of that is being able to run any grade gas
>>to best advantage.
>
>
> no, the *only* thing it has to do is prevent engine damage from knocking.

there's more to gas than octane rating.

>
> You don't program it to run any grade at that grade's best advantage.
> For example, where does that stop? Can I put avgas into my Hybrid and
> the programming will "take advantage" of that?

modern programs run each tank of gas according to each engine sensor's
output and how that complies with what the ecu knows it can do with it.
if its ability to read sensor results for avgas are within its
abilities to manage, then sure, it can run avgas to best advantage. if
it can't, it won't and i'm not trying to tell you i know how the thing
is programmed.

>
> It's designed to run at 86 octane. Yes, the engine management computer
> will prevent damage should lower octane fuel be present, but that's
> different from saying it will change the engine parameters for more
> performance if higher octane is present.
>
> It doesn't do that.
>

i'm not interested in a personal disagreement - i'm only interested in
the technology. i've stated what what i understand to be the current
state of the art, and that /does/ include ability to run different
grades of gas to best advantage. i'm /assuming/ this applies to the
honda because honda have the necessary sensors, ie. knock and crankshaft
angular velocity, [among others]. and they have a good mechanical
design. other than fuel/air charge & ignition, one other big thing in
the performance equation is combustion chamber design. basically, some
designs can only run well with high octane. honda otoh have a design
that fundamentally runs well with lower octanes, but burns higher
octanes very well too - something that's hard to do well the other way
around. from that perspective, the honda /should/ be able to take best
advantage of different grades if it's getting the necessary ecu input
and has sufficient "smarts" to handle it, hence my assumption.

but maybe you /know/ this is not the case.