Unleaded vs Premium Unleaded

Hello all,

I'd be interested in your opinions on this subject.

I drive a Subaru Forrester (bought new) not quite 12 months old with 20,000klm on the clock. I use an injector cleaner periodically. I notice a fairly significant increase in power if I use Premium unleaded fuel vs ordinary unleaded. I know there's about 5 or 6 whatevers used to measure octane rating difference between the two (and thus a bigger bang) but I'm wondering if that's all there is to it?

Also, is it worth paying the extra 10c or so per litre for the extra performance? Is it a cleaner fuel? Does it have any other herbs & spices that the ordinary one doesn't?

I notice from other posts that some of you have worked in the petroleum industry and so await your opinions with interest..:confused:

Cheers,
Keith

I don't know about the techo side of things as far as fuel is concerned but I drive an XR6 ute and definately notice you get more bang for your buck with premium!!
I think in the early XR6's it was the recommended fuel, not sure if it is these days.
Jack.

Keith, we too have the forrester. In the handbook is a supplement which says the vehicle must be run on premium except in Australia. This is based on the assumption that ULP in Aus is 90.9 or higher which it aint. We get at least 60 to 100 km more out of tank of premium so you do the sums. Add to that the cars runs better, doesn't stall and generally has heaps more power. Some BP servos have three types of ULP with the middle one being 91 octane which is less expensive than premium but the forrester runs well on it.

My brother is a mechanic and has had a number of forresters in with complaints of stalling, poor economy and low power. Problem solved by changing to premium.

Cheers

I've found that I get better mileage with premium too. It probably works out about the same price over a long distance, so is worth the extra few cents per litre in my opinion. Our mechanic told us that we should use premium because it extends the life of the injectors. I always fill up with premium.

Have heard that not all premuims are created equal though. Not sure what the story is there, so I await info from the informed.

Thanks for that. Btw, the last lot of premium I got was from a Woollies outlet. You don't suppose that they'd use inferior quality petrol do you?

The premiums like the Shell Optimax and Mobil 8000 have adatives to clean your injectors as well as being higher octane. You also get better combustion at the higher end of the rev range with a high octane fuel. Definately more bang for your buck.

Not available in tassy.
had to sell my Honda Integra Vtir
before moving here. Broke my heart.

im not in the petro industry but my understanding is that when they boil crude oil it seperates - all the more viscious stuff sinks to the bottom and the less vicious stuff rises to the top. they then skim all the stuff off in layers to get the various products. examples are bitumen at the bottom and fuel at the higher end - avgas etc at the top... I also understand that the stuff at the top is more volatile thus "more bang for buck" - therefore the premium must be lighter ? ??? :confused: :confused:

feel free to correct me here - i'm happy to be wrong. I'd like to know if i'm right ..

cheers

Quote:

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Originally Posted by keith53

the last lot of premium I got was from a Woollies outlet. You don't suppose that they'd use inferior quality petrol do you?

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I have been getting the premium - the new Caltex stuff from Woollies and it seem to run my Subi just as good, but I still like to put a tank full of BP in every third or fourth tank.

My car has run almost exclusively on Optimax since I bought it new 5 years ago. At a recent service the guys said it showed. Very clean inside. I can't compare to the regular because I've never put it in there but my son pays the extra for Optimax in a 1990 TRX and says he gets more kms out of a tank so it doesn't really cost any more.

Quote:

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Originally Posted by Zed

im not in the petro industry but my understanding is that when they boil crude oil it seperates - all the more viscious stuff sinks to the bottom and the less vicious stuff rises to the top. they then skim all the stuff off in layers to get the various products. examples are bitumen at the bottom and fuel at the higher end - avgas etc at the top... I also understand that the stuff at the top is more volatile thus "more bang for buck" - therefore the premium must be lighter ? ??? :confused: :confused:

feel free to correct me here - i'm happy to be wrong. I'd like to know if i'm right ..

cheers

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So, the premium is lighter, therefore, the car is lighter with a full tank, hence the better mileage. :D

I've got an AUII - anyone tried premium in one of them for normal driving? Personally, I can't see how it would help your average beast in normal driving because most of the benefits are at the top end of the rev range, but I'm happy to be corrected.

The MG runs on premium, but she's been hotted a bit and isn't a happy beastie on standard dishwater. Mind you, I tend to be a little ... er ... spirited when I drive her.

Cheers
Richard

The higher the octane rating the better the fuel, but it has nothing to do with the actual amount of "octane" in the fuel. Check here for more info http://www.prime-mover.org/Engines/G...es/octane.html
If you put a low rated fuel in a car that needs the high rated juice then the engine will start knocking (igniting at the wrong time) and if you do it long enough you'll stuff the motor. But you can put the better fuel in a regular car and not have a worry. You also used to be able to buy an octane booster to mix with your fuel (probably still can) but from memory the good stuff was $30 for every tank

I have a V6 2002 Vectra ... its said in the manual to only use premium unleaded .... so that is what I do.

I find I get more k's when filled up with the Shell premium (stuff) .... I get it from Shell as they have the 4c off with the docket and it only makes it 6c dearer than the regular.

I have filled up time to time at the local APCO who has its premium at about 4c dearer than regular unleaded and find that the performance and milage is lower than the Shell premium.

My mechanic said that BP has the highest octane and is the best of the premium brands .... no discount docket and no flybuys means that it is Shell for me.

I've got a newish honda accord euro and it runs exclusively on premium. I ran a tank of normal unleaded through once and there was about a 10% drop in fuel economy and a noticeable drop in power.

If nothing else, it is better for the environment too (so I am told). Something about burning cleaner and having less pollutants. Or something like that.

I use optimax most of the time - sometimes the ampol stuff (but it's not as good)

Trav

The octane rating refers to the amount the fuel can be compressed before spontaneously ignition occures lower the octane rating the less you can compress it before it ignites by itself .Not good when it hapens
I run my forrester ( this is the second one) on normal unledded around town , with all the stop & starts economy is at its worst .
But when on a trip or towing the Camper always use optimax more power better economy




The trouble with life is there's no background music.

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Originally Posted by Sir Stinkalot

My mechanic said that BP has the highest octane and is the best of the premium brands .... no discount docket and no flybuys means that it is Shell for me.

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I've got a BP 2c discount card, they just gave it to me when I filled up and I just present it when I don't have any Safeway or Coles vouchers.
Next time you're in a BP outlet ask if they still give them away.
Sorry,, it's for LPG only but might be of interest to some

My little runabout must run on 95+(ST170 Ford Focus), even with the 95 it feels sluggish down low but fill it with opti or synergy(and drive several 100k's to tune too it)and my little 4 scares the hell out of a lot of 8's!
Once I got stuck with normal ULP 3/4 a tank, pinged till I stuck a whole bottle of octane booster in it... @$35 a bottle got barely 300ks before needing more fuel, on the way over(800km)used 3/4 of a tank(optimax).
Moral of the story is if your car has a low compression ratio it may only run smoother... if its high like mine(10.5:1) the extra few cents is well worth it, because milage near doubles.
Compared to europe/japan aust has crap fuel, some imports must be detuned to suit!(for instance PTC's Honda Integra Vtir)

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Originally Posted by Harry72

even with the 95 it feels sluggish down low

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Come on Harry, it is a Focus :D
If you bought a Table saw with a ridiculously undersized motor it would feel slugggish so why do it to yourself with a car :D :D :D :D

Jack

Yeah guess youre right I went from a 5.4ltr BA falcon ute to the 2ltr focus ST... but its not the normal focus as it has 170bhp instead of 120bhp of the normal 2ltr focus(zetec).
If my old ute had the same power per litre as the ST170 it would have 340kw/550nm not 220kw/470nm but thats not a real way to compare as the ute doesnt weigh 2.5 times as much, so power to weight wins... but only just on the 1/4mile if I was to lap both cars around say mallala here in SA the ute would get totally wooped!

Quote:

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Originally Posted by Zed

im not in the petro industry but my understanding is that when they boil crude oil it seperates - all the more viscious stuff sinks to the bottom and the less vicious stuff rises to the top. they then skim all the stuff off in layers to get the various products. examples are bitumen at the bottom and fuel at the higher end - avgas etc at the top... I also understand that the stuff at the top is more volatile thus "more bang for buck" - therefore the premium must be lighter ? ??? :confused: :confused:

feel free to correct me here - i'm happy to be wrong. I'd like to know if i'm right ..

cheers

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I'm not a fuel fella either, but what you put up there sounds correct for quite a few years ago.

Nowadays they have newer refinery towers. Catalytic cracker was what I was told, and they can, within reason, just dial in what they want out of the crude. Say they need a bunch of regular ULP, they can get what would normally come out, and the heavier stuff can be broken up (technical term, don't use it outside your own home.) into more regular. The lighter stuff, I don't know. Some of it stays heavy, some of it is junk, but it works out better in the end for profits, etc.

Told to me by a petrochemical guru, but the details might be as fuzzy as a few beers are likely to make it. ;)

Just out of curiosity, what are they stinging you guys for fuel these days? Here, regular is 122 yen/L, premium 132 yen/L and diesel is about 90 yen/L. Works out to about $1.45, $1.57 and $1.07 respectively, however the petrols are 95 and 100 (don't know how it really compares though) and pretty much sulphur free diesel.

Just gotta get a car than might actually be able to use the good stuff now. The Honda we got now (5 cyclinder, N-S engine, front wheel drive and Camry sized) just aint doing it, even though it's pretty cushy to run around in, as long as I stop touch-parking in the stoopid thing.

Wonder how much a nice new Ute would cost me to import... ;)

Harry.
Honda went like the clappers on Optimax (QLD)
7000 rpm redline 100klm in Second gear.
ulp here is $1.15-9c tas top left hand corner.
It might have run on huon pine wood chips ???

I get noticably better mileage in my Prado using premium but I haven't yet done my sums to see if it is financially worthwhile.

Got told yesterday that Coles Express/Shell will be giving instead of 4c discount
They will give 8c discount to Coles/ Myer card holders

wonder if they will deem this as unfair trading like they just did with liquorland

Quote:

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Originally Posted by ptc

Harry.
Honda went like the clappers on Optimax (QLD)
7000 rpm redline 100klm in Second gear.
ulp here is $1.15-9c tas top left hand corner.
It might have run on huon pine wood chips ???

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Hmmm they must have a little bit higher final drive ratio than mine... 120 in second @7500rpm, not that you need to rev it that far as its a close ratio thru all 6 gears(unlike holdens rediculous 6th gear)

I have an XR6-Turbo. The handbook advises that you can use either "regular' unleaded, or "premium" unleaded....as it is tuned for both.

I have had the car for approx 18 months and have mainly used Shell Premium, but turn into a cheapskate when the fuel cost per litre gets too high. I keep regular figures on petrol consumption as it is a Novated Lease vehicle. I have to tell you that in relation to petrol consumption, any differences are negligable ( in my experience )....54,000k's over 18 months.

I do think that there is a performance benefit in terms of power ( but this may be a perceived benefit ), and "apparently", it is better for my engine.

I run a high compression twin cylinder motorcycle. As it's my work vehicle I very closely monitor the running costs.

One of the ways to observe one of running costs is to take the total cost of the petrol for the year, take the total kilometres travelled, then work out how much the cost of fuel is for every kilometre travelled.

Prior to Shell Optimax coming on the scene, I used normal premium fuel. My fuel cost was almost exactly 5 cents a kilometre. Shortly after Optimax turned up I decided to give it a go, but monitor it carefully.

I noticed after about the third tankfull, I was travelling further on a given tank. I run a large tank on the bike and my fuel range went from about 600 Klm's a tank to about 680 Klm's before starting to need filling up. Eventually I was able to travel about 740 - 760 Klm's before needing a fill. This has merit for anybody who travels in the country, as fuel stations outside of the main roads are quite few and far between.

Anyway, after 9 months of Optimax the fuel cost was still at 5 cents a litre. The extra distance one was able to get from that fuel, negated any price difference.

I have now been using for close to 5 years, different suppliers optimum fuels and have always gotten the same results, whether it is Shell Optimax, Caltex Vortex or BP's version.

If your vehicle is a high performance one, then the better fuel, in my observations, will be the same cost for every kilometre travelled, so there is nothing to be gained there, but you will travel further on a tank, so you gain there.

We also own a Hyundai Excell which runs bog standard fuel. I decided to test it with the premium fuel and found it goes no further on a tank after 4 tankfuls, so I gave it up as I was just throwing money away.

As a point of interest we are currently at the 11 month stage into the financial year. I just did the sums for this year so far, the increased cost of fuel, has finally put the cost up to 5.21 cents per litre. The last 3 years have been steady at 5 cents, so this, the 4th year, is costing more!

Mick.

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Originally Posted by The Thief of BadGags

I have an XR6-Turbo. The handbook advises that you can use either "regular' unleaded, or "premium" unleaded....as it is tuned for both.

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Actually its not tuned for either, the BA is self learning/tunning like my focus... thats why I said after 100km or so its better, you can test this, fill up with a different rating fuel and time how fast your car accelorates or 1/4 mile, when you get towards the end of the tank full you'll find your times will improve by a fair amount and be using less fuel.

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Originally Posted by Harry72

Actually its not tuned for either, the BA is self learning/tunning like my focus... thats why I said after 100km or so its better, you can test this, fill up with a different rating fuel and time how fast your car accelorates or 1/4 mile, when you get towards the end of the tank full you'll find your times will improve by a fair amount and be using less fuel.

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Sorry officer, I wasn't hooning. Honest. Yes, I know I'm too old to be a young hoon but ... It's all the fault of the woodwork forum. Yes officer, I know that I've done four runs down this suburban back street tonight and I know I was doing it last week, and the week before, but officer, this bloke on the woodwork forum. Yes officer, I know that hooning has nothing to do with wood working, but this bloke on the forum, he TOLD ME TO. :rolleyes:

Perhaps Dan P would like to comment on this scenario :D It'd have to be one of the better excuses wouldn't it?

Cheers
Richard

I used to have a 98 nissan pulsar plus. Ran ok on standard fuel, then optimax came out. We noticed the difference in performance, fuel economy and services almost immediately.


Now we've upgraded to a Mazda6. When we bought it, they forgot to fill up the tank, so we put in the Optimax - wonderful, drove like a dream. Next tank they paid for - BP with 10% ethanol. Wasn't happy, drove like crap, splutter stall &*^%$%#* b*********! Back to the Optimax - all systems go!

Cheers
RufflyRustic