High octane fuel and the truth

[moose man]

With so many guys on here talking about using 95 RON, 98 RON and higher, and claiming to make up to 30% difference in power output, and so many others asking whether this more expensive fuel is going to benifit them I just thought I'd start a thread to help educate people and dispel some common misconceptions.

1. If your engine is not designed to use premium fuel, it will not benefit.
When I say 'not' I mean in any noticeable way. Sure, you may get a 0.2 or 0.3% change in fuel use or power output, but it is barely measurable, and certainly not noticeable.

2. Premium fuel is not 'better quality' or cleaner than normal unleaded.
Believe it or not, all fuel comes from the same place. It is all refined and then put into storage containers. Chemists then add chemicals to this fuel to determine what it will be called ie. Premium, ultra, regular etc. In fact, premium fuel has more chemicals added to it than regular unleaded.

The deciding factor for which manufacturers designate the engine to use, is DESIGN. The design of the engine (generally the compression ratio of the combustion chamber) decides whether the engine will NEED high octane fuel, or not. Engines wil compression ratios of 8 or 9:1 do not need premium fuel, nor will they benefit. It's not a choice that manufacturers they make, it's a need.

Standard Commodore engines do not need premium fuel, nor will they benefit from it.

I just hear so many stories of people wasting their hard-earned money on premium fuel and not realising that it's no better than regular. Their mate told them that they got an extra 50 km or 100km from a tank, or they think their car 'feels' better with it. One-off anecdotes unfortunately do not make good proof.

There's one main reason fuel companies push it onto consumers (apart from those few that actually need it), because it is more profitable. More $ for the same product. They don't lie, a 0.08% fuel consumption decrease is a decrease, but they happily leave this data out of the marketing dribble.

If you want to know more about it, then I recommend you read some engineering books, or peer reviewed documents (not a forum or manufacturer's website). Please don't waste your money.

I am happy to answer any questions/comments/disagreements that you may have.

[wraith]

With so many guys on here talking about using 95 RON, 98 RON and higher, and claiming to make up to 30% difference in power output, and so many others asking whether this more expensive fuel is going to benifit them I just thought I'd start a thread to help educate people and dispel some common misconceptions.

1. If your engine is not designed to use premium fuel, it will not benefit.
When I say 'not' I mean in any noticeable way. Sure, you may get a 0.2 or 0.3% change in fuel use or power output, but it is barely measurable, and certainly not noticeable.

2. Premium fuel is not 'better quality' or cleaner than normal unleaded.
Believe it or not, all fuel comes from the same place. It is all refined and then put into storage containers. Chemists then add chemicals to this fuel to determine what it will be called ie. Premium, ultra, regular etc. In fact, premium fuel has more chemicals added to it than regular unleaded.

The deciding factor for which manufacturers designate the engine to use, is DESIGN. The design of the engine (generally the compression ratio of the combustion chamber) decides whether the engine will NEED high octane fuel, or not. Engines wil compression ratios of 8 or 9:1 do not need premium fuel, nor will they benefit. It's not a choice that manufacturers they make, it's a need.

Standard Commodore engines do not need premium fuel, nor will they benefit from it.

I just hear so many stories of people wasting their hard-earned money on premium fuel and not realising that it's no better than regular. Their mate told them that they got an extra 50 km or 100km from a tank, or they think their car 'feels' better with it. One-off anecdotes unfortunately do not make good proof.

There's one main reason fuel companies push it onto consumers (apart from those few that actually need it), because it is more profitable. More $ for the same product. They don't lie, a 0.08% fuel consumption decrease is a decrease, but they happily leave this data out of the marketing dribble.

If you want to know more about it, then I recommend you read some engineering books, or peer reviewed documents (not a forum or manufacturer's website). Please don't waste your money.

I am happy to answer any questions/comments/disagreements that you may have.

Do you have any factual evidence to support these claims?

[sik_dose]

if you look in the owners book of any 90's commodore it will say its tuned to run on regular UPL so the OP makes perfect sense. I would like to see some evidence to back it up as well.

[wraith]

I can only go off personal experience which is by no means scientific. But when I run 98 I get 600 km's to a tank on anything else it's 400 km's. Although I suspect my car is tuned for 98 already as it refuses to run properly on anything else.

[moose man]

hmmm... nothing that I'm allowed to publish online. All too complex and long winded anyway.

I have heaps of books, articles and journals that I studied from, but, being on a forum, this post was more to educate people than to prove or justify my words.

I will, however, answer as best as possible.

[mug1000]

not all cars can run on premium fuels I pretty sure it's the first of the fuel injected for a lot of cars all you have to do is ask someone in the buisness that knows from experience not from a book but for the cars that can run on premium fuels the best for around town is the 95ron for a lot cars becuse it gives you a better drive by waking up the engine and improves you fuel ecconomy slightly with it as for the 98ron is only good for cars that need it and only good for long distance driving for the rest

[Ozzie]

Yeah this is all true.

Basically if you have a standard tune to run 91oct the car will only register the fuel as 91oct weather it be 91 or 98.

Thats why we have smart people like greenfoam out there who re-map our tunes to run the higher octane.

[wraith]

Yeah this is all true.

Basically if you have a standard tune to run 91oct the car will only register the fuel as 91oct weather it be 91 or 98.

Thats why we have smart people like greenfoam out there who re-map our tunes to run the higher octane.

Not always. Some car's can adjust for the better fuels. The Soarer I used to have used to have an interesting way of calculating on reset. I think it advanced or retarded the timing till it knocked then wound it back one step. So yeah.

[Ozzie]

Not always. Some car's can adjust for the better fuels. The Soarer I used to have used to have an interesting way of calculating on reset. I think it advanced or retarded the timing till it knocked then wound it back one step. So yeah.

Soarers come standard with a jap custom tune.

Commodores didnt.

I did mention cars that came programmed as stock for 91oct

[wraith]

Soarers come standard with a jap custom tune.

Commodores didnt.

Yeah. I am no expert but I think the later commodores can run better on higher octane fuel as they can adjust on the fly with the knock sensors.

[Ozzie]

Yeah. I am no expert but I think the later commodores can run better on higher octane fuel as they can adjust on the fly with the knock sensors.

lol nah holdens too cheap for that..
Not sure bout VE's but I know VY VZ were tuned to run 91.

Though the more exotic holdens like monaros and clubbys ect.. were tuned to run the higher octane.

[BowTie]

They are quite bold sweeping claims to make without giving the tiniest hint as to your qualifications or experience.

You speak like a wannabe petrochemical engineer whose knowledge is so far above ours that it would be demeaning to have to explain yourself.

I call bullshit on your hypothesis.

[wraith]

lol nah holdens too cheap for that..
Not sure bout VE's but I know VY VZ were tuned to run 91.

Though the more exotic holdens like monaros and clubbys ect.. were tuned to run the higher octane.

I suppose grandmas can't afford 98 or 95 any way. Good point.

[Ozzie]

They are quite bold sweeping claims to make without giving the tiniest hint as to your qualifications or experience.

You speak like a wannabe petrochemical engineer whose knowledge is so far above ours that it would be demeaning to have to explain yourself.

I call bullshit on your hypothesis.

Criticism will only get you an infraction.

Dont need claims. Ask any good mechanic.

[sik_dose]

They are quite bold sweeping claims to make without giving the tiniest hint as to your qualifications or experience.

You speak like a wannabe petrochemical engineer whose knowledge is so far above ours that it would be demeaning to have to explain yourself.

I call bullshit on your hypothesis.

Have you been pumping your 90's commodore with expensive 98 octane? if i had been i would be calling bull shit to because i hate wasting money.

[Ozzie]

To... BowTie

Here you go if you want to be a smartarse

NRMA Blog

[Robbo VS3]

Just wondering guys, if someone is running standard 91 octane in their vehicle and they want to switch to 95 or 98 octane can you just chuck that on top of the 91 octane, like does it matter if they mix together, or do you need to drain your tank?
My Ute is a V6 Ecotec and i think i remember reading in the manuel that it is tuned to run 91 octane, so thats all i have ever used. However, i have a performance memcal now, and i may need to use 95 or 98 octane with it, or i may benefit anyway.

[wraith]

Just wondering guys, if someone is running standard 91 octane in their vehicle and they want to switch to 95 or 98 octane can you just chuck that on top of the 91 octane, like does it matter if they mix together, or do you need to drain your tank?
My Ute is a V6 Ecotec and i think i remember reading in the manuel that it is tuned to run 91 octane, so thats all i have ever used. However, i have a performance memcal on the way, and i may need to use 95 or 98 octane with it, or i may benefit anyway.

It doesn't matter if they mix. Just remember it will take a couple of tanks before it's pure 98.

[Ozzie]

Just wondering guys, if someone is running standard 91 octane in their vehicle and they want to switch to 95 or 98 octane can you just chuck that on top of the 91 octane, like does it matter if they mix together, or do you need to drain your tank?
My Ute is a V6 Ecotec and i think i remember reading in the manuel that it is tuned to run 91 octane, so thats all i have ever used. However, i have a performance memcal on the way, and i may need to use 95 or 98 octane with it, or i may benefit anyway.

Nah ur good to go. I usually in these circumstances (having a 98ron chip) use a bottle of nulon race formula octane boost if i cant find anything but standard unleaded.

Depending on the tune, My car runs like shit on 91, okish on 95 but smooth on 98

[Calaber]

I can only go off personal experience which is by no means scientific. But when I run 98 I get 600 km's to a tank on anything else it's 400 km's. Although I suspect my car is tuned for 98 already as it refuses to run properly on anything else.

Wraith

Your claims are not credible. You are telling us that your 94 Buick engined VR increases its fuel economy by 50% just by using premium unleaded?

Unless your engine has a much higher compression ratio than standard, or is supercharged, (in which case your economy would go the other way), I can't see any way it's "tuned for 98 already."

But, it's your story and you're entitled to believe it.

[wraith]

Wraith

Your claims are not credible. You are telling us that your 94 Buick engined VR increases its fuel economy by 50% just by using premium unleaded?

Unless your engine has a much higher compression ratio than standard, or is supercharged, (in which case your economy would go the other way), I can't see any way it's "tuned for 98 already."

But, it's your story and you're entitled to believe it.

Yeah believe it if you will I have people that will back my claim but yeah. Maybe it's my cop chip

[greenfoam]

I'm not too fussy on octane on low compression engines but if you have a look at the filter baskets in the injectors on a car that runs on premium rather that 91 octane there's a huge different in how clean they are so don't agree with both fuels being of equal quality as far as keeping things clean goes

[kane88]

I can only go off personal experience which is by no means scientific. But when I run 98 I get 600 km's to a tank on anything else it's 400 km's. Although I suspect my car is tuned for 98 already as it refuses to run properly on anything else.

That seems a little bit too unbelieveable... If everyone could pull those figures in a controlled environment then nobody would buy 91 RON, ever.
Considering most of the information I have come across suggests a few percent benefit, and the fact that the difference in price between the two fuels is a matter of cents, for you to get a 50% improvement is huge, even if tuned for 98 RON fuel. If the premium stuff really did give these sort of results we'd be paying well over $2.00 per litre for the stuff.

What are the variables here? Is that city travel compared to a highway cruise? Did you flog it for the previous tank?

I suppose grandmas can't afford 98 or 95 any way. Good point.

Also, are you calling VY/VZ grandma's cars?
What does that make your VR?

[ephect]

With so many guys on here talking about using 95 RON, 98 RON and higher, and claiming to make up to 30% difference in power output, and so many others asking whether this more expensive fuel is going to benifit them I just thought I'd start a thread to help educate people and dispel some common misconceptions.

1. If your engine is not designed to use premium fuel, it will not benefit.
When I say 'not' I mean in any noticeable way. Sure, you may get a 0.2 or 0.3% change in fuel use or power output, but it is barely measurable, and certainly not noticeable.

2. Premium fuel is not 'better quality' or cleaner than normal unleaded.
Believe it or not, all fuel comes from the same place. It is all refined and then put into storage containers. Chemists then add chemicals to this fuel to determine what it will be called ie. Premium, ultra, regular etc. In fact, premium fuel has more chemicals added to it than regular unleaded.

The deciding factor for which manufacturers designate the engine to use, is DESIGN. The design of the engine (generally the compression ratio of the combustion chamber) decides whether the engine will NEED high octane fuel, or not. Engines wil compression ratios of 8 or 9:1 do not need premium fuel, nor will they benefit. It's not a choice that manufacturers they make, it's a need.

Standard Commodore engines do not need premium fuel, nor will they benefit from it.

I just hear so many stories of people wasting their hard-earned money on premium fuel and not realising that it's no better than regular. Their mate told them that they got an extra 50 km or 100km from a tank, or they think their car 'feels' better with it. One-off anecdotes unfortunately do not make good proof.

There's one main reason fuel companies push it onto consumers (apart from those few that actually need it), because it is more profitable. More $ for the same product. They don't lie, a 0.08% fuel consumption decrease is a decrease, but they happily leave this data out of the marketing dribble.

If you want to know more about it, then I recommend you read some engineering books, or peer reviewed documents (not a forum or manufacturer's website). Please don't waste your money.

I am happy to answer any questions/comments/disagreements that you may have.

how can you say your commodore will not benefit from higher octane fuel and not have facts to back it up? think about it, more fuel, more fire, more intense explosion.. less work = more milage. the delco can adjust to a higher octane fuel, not as much as a car tuned to it but oranges and apples.

hmmm... nothing that I'm allowed to publish online. All too complex and long winded anyway.

I have heaps of books, articles and journals that I studied from, but, being on a forum, this post was more to educate people than to proove or justify my words.

I will, however, answer as best as possible.

why aren't you allowed to publish the facts? how can you educate us just by dictating; this is the truth but im not allowed to back it up with facts?! just believe me...... so your saving that avgas, which is a higher octane, just because it comes from the same refinery will gain you no noticiable results? regardless of tune?
are we talking efficiency of engine or fuel efficiency or just tyre fryin fun?

Me personnally see no reason to pay 15c extra all the time, i'll run a couple a tanks here and there on trips.

[v8commie]

Yeah believe it if you will I have people that will back my claim but yeah. Maybe it's my cop chip

hey cop cars never had a chip i dunno where people got that from they probly feel quicker because they have an lsd they came out with fe2 and lsd thats it