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Premium fuel in the GX470 necessary?

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James P. Clark

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Dec 3, 2003, 8:59:59 PM12/3/03
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I've got a GX470 on order and should be picking it up next week. I know that Lexus recommends premium gas be used, but I'm wondering if there would be ill effects in using regular octane gas instead?

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rubio

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Dec 3, 2003, 10:09:25 PM12/3/03
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trust me you have to use premium and i mean mobile,shell,amoco,thats it
"James P. Clark" <james.c...@SPAMadelphia.net> wrote in message
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markjen

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Dec 4, 2003, 2:36:59 AM12/4/03
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The general rule of thumb on recent cars is that you can use regular, but
you'll reduce performance about as much as you'll save in gas. So if you
don't want/need/use all the performance of your GX, go for it. But it
always seems like weird economy to spend big money on a high-performance
vehicle to feed it cheap gas that turns it into a cheaper, lower-performance
vehicle.

- Mark


John

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Dec 4, 2003, 3:48:56 PM12/4/03
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If you like your car's engine, use premium, it's worth it. I doubt the few
dollars saved relative to the cost is significant... or... penny wise, pound
foolish.


"James P. Clark" <james.c...@SPAMadelphia.net> wrote in message
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MCAS NV

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Dec 4, 2003, 4:39:19 PM12/4/03
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i switched to regular in my '91 LS400 and I haven't noticed anything different
at all. No knocking or pinging at all.

Dan J.S.

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Dec 4, 2003, 5:21:51 PM12/4/03
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>"James P. Clark" <james.c...@SPAMadelphia.net> wrote in message
news:zywzb.8695>$zL1.1...@news1.news.adelphia.net...
>I've got a GX470 on order and should be picking it up next week. I know
that Lexus recommends premium gas be used, but I'm >wondering if there would
be ill effects in using regular octane gas instead?

You do not need to use premium. The engine down-tunes itself for lower
octance gas, with no ill-effects.

Dan


wideglide01...@cox.net

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Dec 4, 2003, 7:51:42 PM12/4/03
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Ignoring his agents wishes,"John" <bou...@here.org> flung open the
hotel room door and announced to the gathering crowd:

>If you like your car's engine, use premium, it's worth it. I doubt the few
>dollars saved relative to the cost is significant... or... penny wise, pound
>foolish.
>

you will *not* damage your engine by going with a lower octane fuel.
You *can* damage your engine by going with too *high* of an octane
fuel for an engine that's not designed for it. Higher octane is to
prevent predetonation in a higher compression engine. If you don't
have a high compression engine or if you're not getting any knocking,
you're not going to lose losing power and your not going to hurt your
engine.


>
>"James P. Clark" <james.c...@SPAMadelphia.net> wrote in message
>news:zywzb.8695$zL1.1...@news1.news.adelphia.net...
>I've got a GX470 on order and should be picking it up next week. I know that
>Lexus recommends premium gas be used, but I'm wondering if there would be
>ill effects in using regular octane gas instead?

**********************************************************************

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safer to harass rich women than motorcycle gangs.
-Unknown


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Carl

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Dec 4, 2003, 8:30:26 PM12/4/03
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If you ask 3 people this question, you'll get 4 different answers.
 
I switched to regular in both my GX and LS430 a long time ago, and have experienced nothing but lower gas bills.  No performance problems, no engine damage, no nothing, just plain old lower costs.
 
Do what you want, and don't let the zealots push you around!
 
Carl

wideglide01...@cox.net

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Dec 4, 2003, 10:13:52 PM12/4/03
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Ignoring his agents wishes,"Carl" <a...@b.com> flung open the hotel room

door and announced to the gathering crowd:

>If you ask 3 people this question, you'll get 4 different answers.

"Are you tempted to buy a high octane gasoline for your car because
you want to improve its performance? If so, take note: the recommended
gasoline for most cars is regular octane. In fact, in most cases,
using a higher octane gasoline than your owner's manual recommends
offers absolutely no benefit. It won't make your car perform better,
go faster, get better mileage or run cleaner. Your best bet: listen to
your owner's manual."

.....however...

"What's the right octane level for your car?
Check your owner's manual to determine the right octane level for your
car. Regular octane is recommended for most cars. However, some cars
with high compression engines, like sports cars and certain luxury
cars, need mid-grade or premium gasoline to prevent knock"

....but....

"Should you ever switch to a higher octane gasoline?
A few car engines may knock or ping - even if you use the recommended
octane. If this happens, try switching to the next highest octane
grade. In many cases, switching to the mid-grade or premium-grade
gasoline will eliminate the knock. If the knocking or pinging
continues after one or two fill-ups, you may need a tune-up or some
other repair. After that work is done, go back to the lowest octane
grade at which your engine runs without knocking."


from: "The Low-Down on High Octane Gasoline"

http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

sf/gf

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Dec 5, 2003, 1:02:22 AM12/5/03
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<wideglide01...@cox.net> wrote in message
news:rflvsvsul9klcrf91...@4ax.com...

>
>
> You *can* damage your engine by going with too *high* of an octane
> fuel for an engine that's not designed for it. Higher octane is to

>
>
> **********************************************************************
>

Please explain how using too high of an octane fuel can damage an engine.
Although it may not make sense from an economic viewpoint, the only
difference between low octane and higher octane is that higher octane burns
slower (which is why it pings and knocks less). Some say higher octane also
has higher detergent levels, but I have never been able to verify this.

For what it is worth, in my GS 300, it recommends premium for best
performance but does not rule out lower octane fuels. I have tried regular,
mid-grade and premium and can not tell any difference in performance. So, I
compromise and use mid-grade. Most modern engines have the ability to sense
knock/ping and will automatically retard the ignition timing to compensate
for the lower octane fuel, with maybe a slight degree of reduced
performance.
Steve


Tsheer

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Dec 5, 2003, 1:20:35 AM12/5/03
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"sf/gf" <sf9...@kart.com> wrote in message
news:ObVzb.29152$sb4....@newsread2.news.pas.earthlink.net...

>
> <wideglide01...@cox.net> wrote in message
> news:rflvsvsul9klcrf91...@4ax.com...
>
> >
> >
> > You *can* damage your engine by going with too *high* of an octane
> > fuel for an engine that's not designed for it. Higher octane is to
>
> >
> >
> > **********************************************************************
> >
>
> Please explain how using too high of an octane fuel can damage an engine.
> Although it may not make sense from an economic viewpoint, the only
> difference between low octane and higher octane is that higher octane
burns
> slower (which is why it pings and knocks less). Some say higher octane
also
> has higher detergent levels, but I have never been able to verify this.
>
Gas doesn't burn "slower" or "faster". The octane rating is relative to
the temperature
at which the gas burns. Higher octane gas combusts at a higher temperature
than lower
octane gas. Compression heats the fuel/air mixture, and if the octane level
is too low
for the engine, the fuel/air will combust from the compression heat before
the spark plug
ignites it. That causes knocking.


markjen

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Dec 5, 2003, 2:05:19 AM12/5/03
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> If you don't
> have a high compression engine or if you're not getting any knocking,
> you're not going to lose losing power and your not going to hurt your
> engine.

Well, this is a chicken/egg argument. No, you're not going to be able to
detect knocking on regular, but that's because the engine has detected it
long before you could, and has reduced engine preformance to elminate it.

So "not getting any knocking" tells you basically nothing about what your
engine is doing or what octane appetite it has.

- Mark


markjen

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Dec 5, 2003, 2:06:50 AM12/5/03
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> Please explain how using too high of an octane fuel can damage an engine.

You're right, it can't. This is an old wive's tale. Using a high-octane
fuel in an engine designed for lower-octane does nothing except waste money.

- Mark


markjen

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Dec 5, 2003, 2:08:04 AM12/5/03
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> You do not need to use premium. The engine down-tunes itself for lower
> octance gas, with no ill-effects.

Except a loss in performance. You may not detect it, but the dyno doesn't
lie - you run most premium engines on regular and peak horsepower drops 10%
or so.

- Mark


markjen

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Dec 5, 2003, 2:10:16 AM12/5/03
to
> from: "The Low-Down on High Octane Gasoline"
>
> http://www.ftc.gov/bcp/conline/pubs/autos/octane.htm

This document says nothing about modern engines with knock-sensors. It is
completely out of date.

- Mark


Dan J.S.

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Dec 5, 2003, 9:29:36 AM12/5/03
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"markjen" <mark.je...@comcast.net> wrote in message
news:o9Wzb.433293$Fm2.434640@attbi_s04...

From some of the reports that I saw, it's more like 2% performance
decrease... I will try to find the article again.


markjen

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Dec 5, 2003, 11:03:27 AM12/5/03
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> From some of the reports that I saw, it's more like 2% performance
> decrease... I will try to find the article again.

C&D is the only definitive test I've seen.

- Mark


sf/gf

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Dec 5, 2003, 8:09:57 PM12/5/03
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"Tsheer" <pos...@use.net> wrote in message
news:PsVzb.30772$9O5.26772@fed1read06...

Agreed. But the flame front actually takes longer to advance (milliseconds)
so there is a slower burn. At least that is how it was explained to me by
my Technology instructor in college. Also, think about diesel fuel for a
moment. Diesel fuel is a light fuel oil and has a lower octane that
gasoline (actually diesel fuel is measured in cetane, if I recall correctly)
It would take a much higher temp to cause diesel fuel to ignite than it
would gasoline, yet by your reasoning the opposite should occur.


Car Guy

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Dec 6, 2003, 6:28:25 PM12/6/03
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I would suggest you look at the owners manual and see what is REQUIRED (i.e. you MUST use) and what is RECOMMENDED (i.e. what is BETTER to use).  I tend to follow the recommended route for fuel and maintenance and in a bind, will follow the required.
 
Not to sound curt, but if you can afford the car, surely, you can afford to gas it with premium :^)

Matt Fournier

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Dec 11, 2003, 11:20:45 PM12/11/03
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It all has to do with the compression ratio of the motor in your car.  The higher the compression ratio, the higher the octane you will need for that motor, with the results of higher horsepower per cubic inch.  If you use to low of an octane, it will or can cause detonation and will cause problems with the piston rings in the motor.  I definitely recommend using the octane required for the car because that's what the engine is designed for.
 
This is why diesel doesn't need spark plugs to ignite.  The octane is so low and the compression ratio in those motors are so high that the diesel self ignites.  Pretty complicated, I've learned because I use different fuels for drag racing, check out more at this website
 

James P. Clark

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Dec 12, 2003, 10:04:20 PM12/12/03
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Thank you all and Matt Fournier for that last post. The link explained the issue very clearly. I will use the recommended gasoline octane for the vehicle.

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hran...@gmail.com

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Nov 29, 2017, 12:45:51 PM11/29/17
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From the Owners Manual:
"Octane rating
Premium unleaded gasoline with an Octane Rating of 91
(Research Octane Number 96) or higher required for
optimum engine performance. However, if such premium
type cannot be obtained, you may use unleaded gasoline
with an Octane Rating as low as 87 (Research Octane
Number 91).
Use of unleaded fuel with an octane number or rating lower
than stated above will cause persistent heavy knocking. If
severe, this will lead to engine damage.
If your engine knocks...
If you detect heavy knocking even when using the
recommended fuel, or if you hear steady knocking while
holding a steady speed on level roads, consult your Lexus
dealer.
However, occasionally, you may notice light knocking for a
short time while accelerating or driving up hills. This is normal
and there is no need for concern.
Gasoline containing detergent additives
Lexus recommends the use of gasoline that contains
detergent additives to avoid build−up of engine deposits.
However, all gasoline sold in the U.S. contains detergent
additives to keep clean and/or clean intake systems."
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