Unleaded vs premium unleaded

[Allan A]

I've often scratched my head at some of the cars I see filling up with
premium unleaded and wonder why they bother. I put it in the high
performance car, but many of the ones at the premium pump are pretty
run-of-the-mill cars.

But I've got a late model Subaru Liberty wagon ('03 model, 2.5l manual) and
a friend who also has a similar age Subi said their dealer said it runs
better on premium, and they think it does, so thought I would give it a
genuine try. I've often heard people claim that "normal" cars go better on
premium.

I live in Canberra, my running consists of a mix of urban commuting, trips
to Cooma, the coast and Sydney. Occasionally I tow a boat or a box trailer,
but the vast majority of the running is just the car with 1 or 2 up. I used
premium (Caltex Vortex) for approx 5,000km, logged every fill, and worked
out the fuel comsumption. Then did the same with normal unleaded, done
approx 3,200km so far. I think I've been doing pretty much the same mix of
running on both lots of fuel.

Now maybe it ran a touch smoother/better on the premium, but maybe it was
just the placebo effect - I have no performance figures on way or another.
But I do have fuel consumption figures. On the premium, 10.07 litres/100km.
On the normal unleaded, 9.78 l/100km. Near as dammit, that's the same
consumption.

No I'm no automotive engineer, but I would think the Subi is probably
reasonably typical of the "normal" range of cars these days.

So I now scratch my head even harder at some of the cars I see at the
premium unleaded pump. I certainly got now advantage on fuel consumption
that would indicate I should be using the dearer fuel.

Would be interested to know if anyone else has done a decent comparison over
some distance, and the results.

Allan A

[dvk]

A good starting point is to do a google search of this group :-)

"Allan A" <aaci@hotkey.net.au> wrote in message
news:429bf1f8_1@news.iprimus.com.au...

<snip>

[jackbadger]

Your spark plugs last longer (are they an cheap & easy change on a Subi
boxer?), & there will be small gains in performance and economy. But
unless you run the engine over identical courses on both fuels, you won't
know by how much.
BTW, Vortex is only 95 octane (i think!), if you really want an
improvement that you'd have to be dead not to notice, use Optimax. They
charge usually a 9-10c premium over normal, where BP/Mobil etc charge an
extra 14c. I've mentioned before here that when I switched our 10YO Toyota
auto over from 91 to 98 octane, my wife noticed enough to ask if I'd done
something to tune the motor! (The only reason for the change was because
I'd heard spark plugs are nearly an engine-out job on the Tarago, and my
employer pays for the fuel!)

[ant]

Allan A wrote:

> Now maybe it ran a touch smoother/better on the premium, but maybe it
> was just the placebo effect - I have no performance figures on way or
> another. But I do have fuel consumption figures. On the premium,
> 10.07 litres/100km. On the normal unleaded, 9.78 l/100km. Near as
> dammit, that's the same consumption.

I don't have any figures, but I hit the trip reset button each fill, so I
can see how I'm going. Vitey is a carburetted car, but when it was pinging a
while back, people said to try PULP, so I did. I honestly didn't notice any
change in performance, and fuel consumption was the usual 400kms - 450kms
per 34-36 litres.

(pinging was caused by crap non-spec spark plugs fitted by idiot dealers at
100,000 kms service as it turned out... Kaos4X4 in Canberra spotted it and
fixed it).

[John_H]

Allan A wrote:

>I've often scratched my head at some of the cars I see filling up with
>premium unleaded and wonder why they bother. I put it in the high
>performance car, but many of the ones at the premium pump are pretty
>run-of-the-mill cars.
>
>But I've got a late model Subaru Liberty wagon ('03 model, 2.5l manual) and
>a friend who also has a similar age Subi said their dealer said it runs
>better on premium, and they think it does, so thought I would give it a
>genuine try. I've often heard people claim that "normal" cars go better on
>premium.

Subaru's recommendation for that engine is a minimum octane rating of
90 RON, which means that plain, ordinary, everyday ULP will work just
fine. There's absolutely no point in wasting extra money to feed it
PULP.

However, it doesn't follow that everything else you might consider as
normal, or run-of-the-mill, is also designed to run on ULP. It's the
manufacturer's design choice that determines what works best, and
invariably the manufacturer's instruction book will clearly indicate
what fuel you should be using. I'm yet to see one that got it wrong.

Disregard the manufacturer's advice at your expense and at your own
peril. It's also best to ignore the dealer's pet grease monkey -- who
may or may not have read the instruction manual. Anyone who can
actually read and claims to know better than the manufacturer's
instruction book is also likely to be full of shit. :)

--
John H

[Shane Brittle]

Subaru's have knock sensors (as do most new cars these days). The ECU
would have recognised the higher octane fuel and advanced the spark
timing accordingly. Consequently you would have had a slight increase
in engine performance with little to no difference in fuel consumption.

When I had a Subaru I always ran it in on Optimax. The car ran smoother
and the engine was less pingy compared with standard unleaded.

[TheTaipan]

Good advice and worth following, however, I have - at my own peril - chosen
to be among the few who risk running my engine on the maximum available 98
ron or a minimum 95 premium if 98 is unavailable where ever I need fuel. I
do so facing the very real risk that my engine may last longer and run
cleaner - without even considering that there may just be a slight chance
that there may be an improvement in efficiency, smoothness and power output
of the engine. Want to play it safe - go by the manufacturer's specs for
the vehicle, don't ask questions, and never, never, expect that a
manufacturer of automobiles could possibly "get it wrong" or be expressing
the bare minimum requirements at all.

SL

"John_H" <john4271@hotmail.com> wrote in message
news:rhtn91t7qtq45gdloq9oi5lpe78qfui4jq@4ax.com...
> Allan A wrote:
>
>>I've often scratched my head at some of the cars I see filling up with
>>premium unleaded and wonder why they bother. I put it in the high
>>performance car, but many of the ones at the premium pump are pretty
>>run-of-the-mill cars.
>>
>>But I've got a late model Subaru Liberty wagon ('03 model, 2.5l manual)
>>and
>>a friend who also has a similar age Subi said their dealer said it runs
>>better on premium, and they think it does, so thought I would give it a
>>genuine try. I've often heard people claim that "normal" cars go better on
>>premium.
>
> Subaru's recommendation for that engine is a minimum octane rating of
> 90 RON, which means that plain, ordinary, everyday ULP will work just
> fine. There's absolutely no point in wasting extra money to feed it
> PULP.
>
> However, it doesn't follow that everything else you might consider as
> normal, or run-of-the-mill, is also designed to run on ULP. It's the
> manufacturer's design choice that determines what works best, and
> invariably the manufacturer's instruction book will clearly indicate
> what fuel you should be using. I'm yet to see one that got it wrong.
>
> Disregard the manufacturer's advice at your expense and at your own
> peril. It's also best to ignore the dealer's pet grease monkey -- who
> may or may not have read the instruction manual. Anyone who can
> actually read and claims to know better than the manufacturer's
> instruction book is also likely to be full of shit. :)
>
> --
> John H

[Charlie]

my falcon ran better on premium because the 10 year old injectors were
about 20% down on flow, causing it to run lean and ping. Fixed the
injectors and it drives much better, and on plain unleaded. The rx7
gets premium because pinging scares me, any extra buffer is good to
have. With the number of cars I hear up my hill that ping their heads
off, it doesn't surprise me that plenty of people find premium better.

Charlie

[Hugo-a-Gogo]

On Tue, 31 May 2005 15:13:02 +1000, "Allan A" <aaci@hotkey.net.au>
wrote:

>I've often scratched my head at some of the cars I see filling up with
>premium unleaded and wonder why they bother. I put it in the high
>performance car, but many of the ones at the premium pump are pretty
>run-of-the-mill cars.
>

Tried PLUP off and on for 5 years over 4 GEN III V8's can't say I
notice a difference.

Perhaps if you monitered very scientifically... but no apparent
noticable difference in every day use.... I mean it certaily doesnt
seem to give more power or smoother running.

[DalienX]

Allan A wrote:

> I've often scratched my head at some of the cars I see filling up
> with premium unleaded and wonder why they bother.

I know for a fact that i get better economy with premium in the VS



--
DalienX

[Scotty]

With regular unleaded I get 400(ish)kms per 65 litres in my Hiace, with BP
Ultimate I get a regular 40-60kms more.


"DalienX" <somewhere@earth.com> wrote in message
news:pIVme.8041$BR4.1322@news-server.bigpond.net.au...
> Allan A wrote:
>
>> I've often scratched my head at some of the cars I see filling up
>> with premium unleaded and wonder why they bother.
>
> I know for a fact that i get better economy with premium in the VS
>
>
>
> --
> DalienX

[Rainbow Warrior]

"Allan A" <aaci@hotkey.net.au> wrote in message
news:429bf1f8_1@news.iprimus.com.au...
> I've often scratched my head at some of the cars I see filling up with
> premium unleaded and wonder why they bother. I put it in the high
> performance car, but many of the ones at the premium pump are pretty
> run-of-the-mill cars.
>
> But I've got a late model Subaru Liberty wagon ('03 model, 2.5l manual)
and
> a friend who also has a similar age Subi said their dealer said it runs
> better on premium, and they think it does, so thought I would give it a
> genuine try. I've often heard people claim that "normal" cars go better on
> premium.

My TB42 runs better on PULP, tends to ping & run on using ULP since I tuned
it for PULP, spins a lot better at 6500rpm with good fuel.

Fuel economy, don't give a stuff, I only do 400km per month.

[sheik yerbouti]

On Tue, 31 May 2005 17:54:24 +1000, Charlie <askme@nospam.org> wrote:

>my falcon ran better on premium because the 10 year old injectors were
>about 20% down on flow, causing it to run lean and ping. Fixed the
>injectors and it drives much better, and on plain unleaded. The rx7
>gets premium because pinging scares me, any extra buffer is good to
>have. With the number of cars I hear up my hill that ping their heads
>off, it doesn't surprise me that plenty of people find premium better.
>

the other option of course is to tune up your engine

---
sheik's auto service centre
88 Wilsons Rd Doncaster 3108
(03) 8855 8077, http://www.freewebs.com/sheik_yerbouti
specialising in transmission service
5% discount if you say you saw us on aus.cars

[AJS]

"Allan A" <aaci@hotkey.net.au> wrote in message
news:429bf1f8_1@news.iprimus.com.au...
> I've often scratched my head at some of the cars I see filling up with
> premium unleaded and wonder why they bother. I put it in the high
> performance car, but many of the ones at the premium pump are pretty
> run-of-the-mill cars.

If you really are interested then do a google archive search. This has been
rehashed many times.
In some cars it works well in others it doesn't. None of the cars I've tried
(quite a few) like Vortex but the BP is has always shown a noticeable
effect. The "oxygenated" fuels are known to increase detonation in some
cars, mostly high compression worked motors.



AJS

[Charlie]

sheik yerbouti wrote:

> the other option of course is to tune up your engine

and what would you suggest oh font of automotive wisdom?

Charlie

[Michael C]

"Charlie" <askme@nospam.org> wrote in message
news:429C1830.F2B08ED5@nospam.org...
> my falcon ran better on premium because the 10 year old injectors were
> about 20% down on flow, causing it to run lean and ping. Fixed the
> injectors and it drives much better, and on plain unleaded. The rx7
> gets premium because pinging scares me, any extra buffer is good to
> have. With the number of cars I hear up my hill that ping their heads
> off, it doesn't surprise me that plenty of people find premium better.

I'm still undecided if it makes any difference in my rx7.

Michael

[Charlie]

Michael C wrote:

> I'm still undecided if it makes any difference in my rx7.

I doubt it makes any driving difference, but it *could* be the
difference between a busted apex seal and a nice country drive, the next
time my fuel filter clogs up, a hose pops off, etc etc...

Charlie

[Charlie]

Shane Brittle wrote:
>
> Subaru's have knock sensors (as do most new cars these days). The ECU
> would have recognised the higher octane fuel and advanced the spark
> timing accordingly. Consequently you would have had a slight increase
> in engine performance with little to no difference in fuel consumption.

getting better engine performance for the same amount of fuel, means for
the same level of performance (100km/h on the highway etc) you need less
fuel...

Charlie

[sheik yerbouti]

On Tue, 31 May 2005 21:52:11 +1000, Charlie <askme@nospam.org> wrote:

>sheik yerbouti wrote:
>
>> the other option of course is to tune up your engine
>
>and what would you suggest oh font of automotive wisdom?
>
the other option of course is to tune up your engine


---
sheik's auto service centre
88 Wilsons Rd Doncaster 3108
(03) 8855 8077, http://www.freewebs.com/sheik_yerbouti
specialising in transmission service
5% discount if you say you saw us on aus.cars

[Bob Saccamano]

<Hugo-a-Gogo> wrote in message
news:rf8o91lop8iqvo3t7bcuo9ks16jmcbu2g7@4ax.com...
> On Tue, 31 May 2005 15:13:02 +1000, "Allan A" <aaci@hotkey.net.au>
> wrote:

> Tried PLUP off and on for 5 years over 4 GEN III V8's can't say I
> notice a difference.

Interesting, my GenIII (unedited) loves the stuff (98). Far smoother,
noticeably more responsive, but the jury's still out on fuel consumption. It
even "sounds" livelier at WOT.