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by John Cadogan

Non-car enthusiasts are very confused by this question. And the fuel companies haven’t helped – the number of different retail fuel products beggars belief.

In the past few years we’ve seen an explosion in the number of fuel products – many of which bear absolutely no resemblance to the way fuel is actually specified by car manufacturers.

Pop open the fuel flap on a contemporary car and you’re likely to see “Uleaded Fuel Only” inside the flap. Other options include “Premium Unleaded Only” or “98 Octane Unleaded Only”. Imagine how confusing that is when someone in an unfamiliar car pull up at a servo, next to a pump marked ‘V-Power’ or ‘Bio e-Flex’. It can be a difficult code to crack, for the uninitiated. There are consequences – sometimes severe ones – if you get this wrong. You could easily blow up your engine, or cause thousands of dollars worth of damage.

There are currently five different ‘flavours’ of automotive petrols on the market, if you discount the 100-octane leaded avgas sold near some aboriginal communities to discourage recreational sniffing. The widely available mainstream petrol blends are sexed up with a hodge-podge of different brand names for retail sale in the same way, for example, orange juice manufacturers try to differentiate themselves from one another even though it’s really all the same swill, basically. No two fuel brands use the same name for their basic unleaded petrol, even though it is all often produced by exactly the same refinery.

Automotive fuels currently on offer include:

Standard unleaded petrol (ULP), which has an octane rating of 91 and is being phased out in some states, soon to be replaced by E10. It’s the fuel most petrol cars on sale in Australia require. (It’s the one that goes with the ‘Unleaded Fuel Only’ sticker inside the fuel filler flap.)

E10, which is a blend of 10 per cent ethanol. Most modern cars can run E10, as well as many older cars. If unsure, check with the vehicle manufacturer. Older cars might not have E10-proof materials inside the fuel systems. The E10 can, in these cases, break down these incompatible materials and the byproducts of that breakdown can become dislodged and migrate upstream where they can clog the fuel filters and injectors, which is an expensive problem to solve.

If you’ve been using 91 ULP and it’s become unavailable in your area, and your car is incompatible with E10, you’ll have to use the next fuel in our list, a premium unleaded petrol, which is more expensive. (interestingly, E10 can also damage mowers and other yard equipment in the manner described above. It’s generally a safer bet to run these items on a premium unleaded fuel. (They consume very little, so the running cost difference is negligible.)

E10 will help a suitably compatible 91-octane-minimum engine perform a little better, too, allowing the engine to advance the timing a little, but it packs less energy into every litre, so your fuel consumption invariably goes up, offsetting most of E10’s upfront price discount. The performance increase will be very minor, and the consumption goes up 3-4 per cent.

Premium, 95-octane unleaded petrol (PULP). This is the first of two ‘flavours’ of PULP, and is the entry-level fuel in some other markets, like Europe, which lacks 91-octane. If your car says ‘Premium Unleaded Only’ inside the filler flap, this is the one you should use – if you use 91-octane or E10, serious, expensive engine damage might result. This 95-octane stuff is the cheaper of the two PULPs.

Premium 98-octane unleaded (PULP). This is the fuel demanded by some exotic cars, often with forced induction (turbo or supercharger induction) or ‘direct injection’, and the most expensive petrol on the market. If the car says ’98-octane Unleaded Only’ you must not use any of the lesser petrols, because you could severely damage the engine, landing you with a bill an ordinary mortal might not jump over, given the nature of some of the cars that require 98.

E85, a blend of up to 85 per cent ethanol, with the balance in petrol. The recipe varies by place and season; it’s not always 85 per cent ethanol. Currently this fuel is available only at some selected Caltex servos and is called ‘Bio e-Flex’. The only cars – so far – that can run it are the latest ‘Flex Fuel’ iterations of Holden’s Commodore. If you stick this green-oriented fuel in basically any other car, chances are you won’t get it started at the next cold start. Cue the expensive repair bill again.

Here’s the thing: you can put a higher octane fuel in a car than the manufacturer’s requirement. No problem with putting 95 or even 98 in a car designed for 91 – except generally you will be wasting money. Higher octane fuels don’t contain more energy. Octane rating is basically resistance to burning under pressure, allowing higher compression ratios to be used (cylinder pressures, actually). A modern engine designed for 91 will even deliver a very small amount of additional power if fed 95 or 98 because it will advance the timing a little more than with 91. The improvement will be very minor. So minor you probably won’t notice it.

Most engine design experts I’ve ever spoken to regard running higher octane fuel in an engine designed for a lower octane fuel as basically a waste of money.

However, it’s an unmitigated disaster to put a lower-octane fuel in an engine than the one recommended by the manufacturer. This can lead to severe engine damage. The early detonation of the fuel can raise the temperature inside the combustion chamber to levels that the metal parts inside the engine can’t withstand, and unacceptable stresses are also placed on internal components.

One fuel manufacturer that has recently taken a real step in the right direction is Caltex, which has taken the decision recently to display the meaningful numbers – 91, 95, 98 – on every bowser. It’s really useful information to help ordinary consumers cut through the branding to the essential information.

  • Animbo

    A good article John – many people don’t really understand the consequences of putting poor quality or lower octane fuel in a modern car. I would have thought also mentioning Diesel in your article might prove useful. The consequences of unleaded in a Diesel car are probably even worse than putting E10 or 91 in a 98 RON car.

    • nickdl

      Yep, petrol in a diesel is very expensive, especially if the car is European. I’ve had two friends do that in their cars, a Citroen and an Audi, 5 grand each to fix…

      • Nath746

        A while ago, I was with a group of friends and we were in a Toyota Hiace Diesel Bus. One person who drove the bus only had an Unleaded car, and accidently put Unleaded Fuel into the Tank. The Bus started fine (because of the diesel fuel in the lines still) and drove fine as well. We drove for about 150 kms on unleaded fuel before we had to come to a stop (intersection in a town). The bus stalled and we could not get it started again.

        It was an easy fix though – The bus was left to sit and then the fuel was drained out. And it definately didn’t cost $5,000.

        • Nat

          i doubt your toyota hiace had the technology the new diesels have with high pressure injectors and all the other things that can go wrong

        • Reckless1

          You shouldn’t brag about the stupididty of your self and your group of friends on a car enthusiast’s forum.

          Why didn’t anyone, especiall you, notice that the dufus was pumping the wrong fuel.

          The Toyota injector pump will certainly have been badly worn and it will end up costing $5000 to fix.

          The only way it will have escaped is if your dufus added 20 litres of ULP to top up the tank which still had 80+ litres of diesel in it.

    • Mainman

      your friends are lying or got riped off hard.
      Its an easy fix as long as you dont go driving around because it could cost alot more. (your life)

      • nickdl

        Yeah they didn’t realise until the car stopped. Citroens and Audis are about the two most expensive to fix for anything, and with all of the modern technology there is no way that you’d want anyone but a dealer to fix it. Plus the Citroen broke down in the country so had to be towed back to Melbourne which added to the cost.

    • Sean

      I agree i have seen a lot of people that have mercedes benz cars just use regular unleaded i told one mercedes benz owner the car engine isn’t designed for regular unleaded and i said from 95 octain or higher or it would cost a lot of money to rebuild the engine so he put 95 octain unleaded in it and he thanked me to let him know and my mother had a mercedes benz motor rebuilt and the car wasn’t one year old by using the wrong unleaded fuel but the motor was covered in the insurance and it cost around au$13,000 in 1991 and that was a strait 3.0 litre 6 cylinder and anyone with European cars use 95 octain at the lowest. In europe regular unleaded is 95 octain and the reason i know this because i went to europe in 1990 and don’t put e10 in the cars and check with the service department. 

  • Shak

    Great write up John, as these sorts of problems do a lot of damage for a lot of people. i’vs had it happen in my family a couple of times.

  • gearboxdawg

    Very informative article. A dealer service guy once told me if you use PULP or RON 98, engine wouldn’t have as much carbon as using 91. Save money on decarboning.

    • Fenno

      A lot of the current high octane fuels also have cleaning additives in their brews as well. THis may give the impression to somebody with an older car that the vehicle is running better due to the octane, but it is in fact the cleaning properties weaving their magic.

      Most modern cars with Variable valve timing systems will respond better to higher octane as they run (usually) a couple of knock sensors that detect pinging and retard the timing to suit the quality of the fuel. Bear in mind that they still set a base rate for timing so like John has mentioned, going under will cause grief.

      Also, manufacturers that state a given fuel quality (ie VW) will have the fuel tested for quality if warranty concerns on mechanicals can be traced to fuel.

      From experience stick to the big 4* for consistant quality and avoid the independants as much as possible. (Some are known to use other nasties like toluolene to bump up the rate of inferior blends – and can be a health hazard).

      *Caltex, BP, Shell & Mobil

    • benny

      maybe dont drive like a baby boomer all the time and it wont build up heaps of carbon

  • Andrew

    In my old 97 Toyota Starlet using 91 fuel it would make a drinking/pinging noise under acceleration up hills, using 95 this noise was only very faint mostly eradicated. Did not seem to notice any change in performance or fuel economy but have been using it ever since including in my new car. In a car that was designed to have its performance enhanced by use of 98 fuel (eg. FG Falcon) I would use that as it seems more widely available then the not rare but scarcely available 95-octane. If it was a choice between 91 or 98 then 98 anyday.

    • Damo

      My girlfriend had the same pinging problem with her Starlet when I first meet her. She had taken it to several mechanics. They I told her to try 95 or 98 octane fuel and the noise went away.

    • Zain287

      I have the same car, the noise went away with united unleaded knly and their e10… I’m using e10 UN my starlet life 97 I’m losing engine oil…. Is it e10 causing tits problem ?

  • Nat

    Well id have to say in one of my cars v8 ssv ute i ran 98 all the time and one day i had to run 91 because it was the only fuel i could get and i noticed about 50 – 80ks diff out of the tank and it happened on a couple of occasions where i could only get 91 so i know from experience i get better economy from 98 octance

    • Mark

      Yeah, no mention of the economy benefits of using 95/98 in a 91 octane rated car.
      I also get more km’s per tank using higher octane fuel.

      • Nat

        Well i had a 09 VE SSV commodore ute 6L V8 and i think they are made to run on about the lowest grade fuel but i always ran 98 octane and the few occasions had to use lower grade i noticed i got less kms from the 91 so yeah i know for a fact i could get better economy from higher octane!

        • MattW

          As long as the economy improvements are enough to match the extra you pay on the fuel… I think the difference when I put some in during the week was something like $1.20 > $1.40, so in that case you would need 16% improvement in economy (which I very much doubt you would get) to break even over using the cheaper fuel

  • Dennis

    I’m sure United Servo’s sell E85? Not sure how many stores actually stock it…

  • James

    Diesel anyone?

    • Nat

      diesel is awesome how powerful the european diesels are i dont think there will be a need for most petrol models, im pretty sure diesel bmws outsell the petrol alternatives!

      • Al Juraj

        But Aussies still buy more 320i cars than 320d. Many still believe diesel isn’t good, and the slightly higher price discourages them. What they don’t realise is how far it has advanced. What used to be rough and noisy is now quite tolerable. And what BMW is offering is just plain brilliant. In a few years, they’ll be able to make them rev more, which is the only downside I can see at the moment.

        • Save It for the track

          Not only BMW, but VW as well. In Europe diesel has long outsold petrol. One thing you are overlooking though is the leaps in fuel economy and driveability of small capacity turbocharged and supercharged vehicles from VW, Fiat and others which are getting closer and closer to similar sized diesels in terms of fuel economy.
          What will be interesting to watch in years to come is whether we get more use of bio-diesel and non fossil fuel related diesel in Aus. At the moment bio-diesel is not widely available and is not suitable for many of the advanced common rail diesels from Europe. With manufacturer recommendations ranging from “don’t use it”, through to only blends of 5% or less or thereabouts.

          • Nath746

            The good thing about the diesel cars is that there is only currently one type of diesel variant widely available. The thing with the Smaller capacity turbocharged and supercharged engines from europe is that they all require premium unleaded fuel, which some owners can find confusing

          • Who Knew

            Well certainly diesels have improved over recent years, but they are still a poor idea from the view of running costs. The extra purchase price, greater servicing costs, more expensive fuel cost and greater depreciation means that it takes way too long to amortise through the improved economy. Often this is much longer than the economic life of the vehicle, so in the long run diesels still end up costing you more. Diesel cars may be a better proposition second hand, but as a new car, you are just throwing your money away.

            No one seems to have mentioned that the reason diesels are so popular in Europe is that the tax on diesel fuel is much less that it is in petrol and so the fuel is much cheaper and it makes the sums much better

        • Devil’s Advocate

          Sure, they may sell more 320i models than 320d models (which IMHO is crazy as the “d” is so much better) however as a whole BMW sold more diesels than petrols in the month of October when you include the whole range and this trend appears to be increasing. Don’t forget BMW sell more than just the 320i/d… When it comes to their popular X models, diesels are king by a long way.

          • Nat

            Yeah your right about diesel a lot of people still believe that diesel is a bad slow sounding engine, i would say bmw make about the best diesel engines around i recently drove and looked at a new bmw x5 40d twin turbo diesel and its just amazing dont think anyone would have guessed a 3.0L diesel could do 0-100kms in 6.6 secs. Yes VW is also leading the way in top quality diesel engines to and as in europe they do sell alot more diesels than petrols. As for smalled turbo and petrol engines that might be good in the short term but they just dont have the torque to offer like a diesel does they maybe getting close to diesels economy but wont get that close. I was chatting to the people at the bmw dealer and they said they havent ordered let alone sold a petrol x5 for atleast 5 years no one wants one with the exception of the x5m which is mad but for just everyday cars diesel always wins in their sales.

        • golfer

          A colleague bought a 320I because they had a long wait on the 320D. On top of that they threw in extras to get the sale.
          The 320D is a far superior vehicle in almost every respect, but some people just can’t be told.

        • Sean

          I would buy a diesel car over a petrol with the low end toque and i wouldn’t buy a car if there isn’t a diesel version like honda and Toyota in there cars except the 4wd’s and i have had diesel Toyota Prado and it went very well and the fuel consumption is a lot better. My father brought the v8 twin turbo diesel 200 series landcruser and it’s very responsive with 260 hp and has trouble keeping it at 110 km/h on the highway with the engine spinning at around 1800 rpm and it redlines at 4600 rpm for a 4500 cc engine and it has a very nice sound to it for a diesel. That engine in a toyota Prado would be very impressive.

  • Gan Tan

    Whats frustrating is the sheer lack of 95RON pumps at servos recently as the E10 ones are pushing them aside, which either forces me to try E10 (which I would never use) or pay up and get 98RON

    • Mark

      Yep, agreed. This is getting frustrating.

  • Jacked

    United servos mark their E10 as 95 octane but the Caltex E10 is 91 octane. Whats up with that?

  • Devil’s Advocate

    Just one thing WRT E85 and the statement “The only cars – so far – that can run it are the latest ‘Flex Fuel’ iterations of Holden’s Commodore.”
    I was under the impression that all petrol model Saabs sold in Australia have been compatable with E85 since mid 2009? I remember stories about them on the news/in magazines last year and have seen it on multiple websites etc. Then again, Saab sell so few cars now that their numbers are insignificant!

    • Fenno

      Yes the Saab ecopower was e 85 tolerable but rarer than rocking horse poo.

    • Jeff

      Dodge journey v6 has been e85 compatible since it came down under and these are not as rare as rocking horse poo

  • forget-me-not


    • Travis Hammond

      no need to include LPG… good luck trying to find the wrong LPG at a servo, and if you can get some ULP into your LPG tank, you deserve a prize.

  • laurie

    One reason why my diesel Mondeo will never have the wrong fuel put into it brilliant idea the capless System accepting only diesel nozzel maybe Ford has a patent on it!


    • Bob

      They do mate, and it’s a genius system.

  • Mick

    I believe that fuel rated at 95 or moreso, 98, often have a different or stronger additive package added by the fuel company. You won’t get much benefit from it being 98 octance alone, unless you have engine knocking, but it can burn clearner and over time give you overall better economy since it has the built in cleaners. During the middle of summer when it can be very hot (think 45C+!!) in some places of Australia, 91 fuel is much more prone to pre-detonation, resulting in damage to the engine. This is particularly true with an engine under load.

    In terms of ethanol added fuel, ethanol increases the octane rating of the fuel slightly, such that 91 octance becomes 94 octane, and 98 octane becomes 100 octance (available at some service stations). If an e10 fuel is rated at anything lower than 94, it means the base fuel is actually lower octane (and most likely quality) than normal unleaded, and the ethanol was added to make it appear higher quality than it really is. Avoid any standard E10 ULP thats below 94!!!

    Ethanol is a bit of a con, and in fact there is a much better but under utilised alcohol fuel called butanol which produces better results. Butanol is almost as energy dense as petrol, doesn’t attract water as easily (very beneficial), and can run at much a higher percentage blend than 10 percent completely safely! It is the only true alcohol based alternative that should be utilised. I believe the octane boost is less than ethanol, but it still raises the octane level. I truly believe butanol technology should be utilised since it really is so much better than the ethanol ‘con’ :)

  • Will

    Gosh, talk about back dated. Anyway, I use diesel and have noticed there is a premium diesel in the market. What is the difference?

    • Fenno

      Caltex and BP offer at select stations a Premium diesel.
      I have a Polo diesel that runs quieter and smoother on the premium brew and gives me another 50km.
      Like petrol, Diesel has a rating but it is called the Cetane Rating (not the octane rating). Iassume the premium diesel has a better cetane rating for modern common rail/pump dusche diesel engines.

      • Will

        Thanks Fenno,
        I now shall actively seek out BP and Caltex.

    • Biker

      I believe the diffferent diesels fuels are to do with the sulpher content. The premium versions have something like 50-500 parts per something. Not sure about in Oz, but most likely the standard diesel has sulpher content of between 500-5000 parts per something…
      Very old versions of diesel was much higher and the reason also why oil service intervals for diesels were shorter. I.e. improved diesel quality reduced service intervals. Not that it matters in OZ, as you will probably have to service the vehicle before \”international rated\” interval occurs.

  • John

    E10 is a rip-off. My business runs a 2007 Mazda Genki, which gets 50km a tank less out of a tank now using E10 which works out at 5 – 6% less consumption fo a saving of 1.6% saving in cost. Someone is making a fortune out of this racket, either the government or the fuel companies. Now that 91 has been phased out I would bet that the price differential dissappaers as well. Most cars I have had over the last 10 years have gained almost sufficient extra km’s from 95 to justify the extra cost. My current car specifies 98 which at our garage is 17c dearer than E10, another rip-off.

    • Jeef Beef

      The NSW is mandating the phasing out of all 91 Octane pumps for ones with E10. They are justifying it as part of being ‘environmentally aware’.

      Guess who’s raking in the extra taxes?

      • Shak

        How would they be making more tax money, when E10, should theoretically have 10% less petroleum content, and therefore the taxed component of the fuel should be lower? Correct me if i am missing something here.

        • Max Power

          Because you get less mileage from E10, so you use more litres of fuel each year, so they make more money in taxes, as you are going to the bowser more often. Also, I doubt the Govt will charge less excise because it has 10% less petrol in it. Lets not forget the GST on petrol also.

      • Fenno

        Guess who’s propping up a failed sugar industry thanks to our “free trade agreement” with the Yanks(on everything but sugar).

  • http://caradvice craigMM

    I use 95 in a stock Vy V6 and notice a slight increase in response when accelerating from standstill compared to 91. Its enough of a difference to pay the extra. On a 150km freeway run ive managed 7.7ltr/100km(according to the computer) compared to 8.2ltr/100 on 91. So I believe it has increased power slghtly resulting in less throttle when cruising.

  • Joe

    Just for the record, you can run E85 in almost any car. There are a few caveats though.

    – At the same settings as per ULP, the car runs extremely lean. You therefore require more fuel to be mapped in and this can only be done with a programmable ECU or a reflash of the stock one.

    – As a result of the above, you will require bigger injectors and fuel pump to suit.

    – You can run a lot more ignition timing due to the extremely high octane (110+), and it is almost detonation proof in a performance application.. more timing increases power and torque massively. I’ve seen a 60nm jump in torque in my WRX, just from the E85 fuel on the same boost.

    – Fuel consumption goes out the window.. increased by around 20%

    – Some cars have not got fuel lines that will handle E85, but from anecdotal evidence, a lot of cars will be able to handle it with no fuel line breakdown. No guarantee that your car can or can’t though!

    It’s ideal in a performance application, being detonation proof and a basis for making huge HP, and in the states where it is on pump, its the best choice for high powered modified cars.

    • Joe

      Oh, and where I say “states”.. I don’t mean the USA, but Eastern States where it is available at the pump. It’s not in WA right now, which means I have to buy mine in CSR branded 205L drums (same fuel as used in the V8 Supercar series).

  • Banicks

    Nothing but 98 goes into mine. Efficient and better for the engine.

    The rest are just watered down gimics to make more profits for petrol companies.

  • Samr

    I have a Pulsar SSS and now I have to run it on 95ron as 91 is getting scarce.

    10 cents a litre more for no environmental gain and maybe a negative one from some stuff I have read.

    Greenies have a lot to answer for.

  • RC

    Can anyone explain why in Aus, the hold clips on fuel nozzle triggers have been removed? I’ve done a fair bit of travelling in my life & nowhere else is that the case. After living in Europe for the last 5 years, atleast you could leave the car to fill by itself whilst attending to the checking of oil, water, cleaning windscreens etc. Here you have to stand like an idiot holding the trigger in, wasting your own time & everyone else’s.

    • pb

      Yeah. Standing there while putting 160 litres into the Prado is a pain – I usually shove the fuel cap into the handle to hold the trigger in. Mind you, the ‘high flow’ pumps have the little clip things.

    • golfer

      It’s illegal as it’s regarded as a safety hazzard.
      Fuel station attendents are encouraged to turn off pumps if they are left pumping unattended (i.e. fuel cap locking the handle on).
      IMHO it’s overkill, but I’m not the dude working at the fuel station.
      On another note, according to my local firemen, it’s amazing how many people that have their car catch fire, will actually drive into a service station!

    • Michael

      It’s all about static electricity. Anyone driving a car should do a bowser safety course.

    • Sean

      carry a nail in the car and it works very well.

  • Biker

    Octane in fuel for me determined the ignition point. In the year dot before unleaded, 91 octane was the only fuel available at altitude(abroad and at 1500-1800m above sea level). Due to the reduced air pressure, 91 octane was the only option. Only when you got to coastal towns were 95 octane available and the improvement in performance was noticable. using 95 octane at altitude was just a waste, same for using 91 at sea level.

  • Mainman

    The fuel from a petrol station works for me.

  • Rick2

    Don’t forget that fuel quality can vary from batch to batch. My wife’s brand new 1.6 litre petrol Fiesta started pinging (pre igniting) like mad after the first 1000k’s. The recommended fuel is 91. The dealer recommended a tank of 98 on the next fill – instant fix. She’ll fill up with Premium every 4 fills or so. And it;s not just 91 that doesn’t make the grade sometimes. My 2001 M3 demanded 98 but used to ping when poor fuel supposedly 98 went in. I had to resort to Octane Booster to cure that. It would be v interesting to follow this up with random testing of some fuels to see if their advertised Octane rating is actually being delivered.

  • James

    My Celica only takes ‘Premium unleaded fuel only’, and I use BP Ultimate (98) whenever I fill up. People are always questioning why the car can only take premium.

    Can anyone clarify what 91 does/does not contain to damage the engine?

    • half

      There’s more “kick” in higher octane fuel.

      Using 91 won’t damage the car, it will just run sluggish and use more fuel.

  • danno

    Can someone explain to me why we need to use 98 Octane fuel in some cars (Our Ralliart Lancer for example), when most cars here that use 98 are sold in the USA with the same power rating, yet the highest grade of fuel they have is 92 (lowest is 87) Octane. Also, wasn’t there a story going around that it doesn’t cost 20c more a litre to manufacture 98 (compared to 91). The next article should be an exposé!

    • Luke

      They use a different type of octane rating in the US. Their 87 is the equivalent of our 91 RON and their 92 is roughly our 98. There’s an article about the octane rating in Wikipedia.

  • jonk

    I’d make an adjustment to your article about putting premium unleaded in mowers etc

    You can cause a lot of damage mixing two stroke with premium. They become incredibly hard to start.

    • Sean

      You can mix premium unleaded with 2 stroke oil and i have had 2 a stroke outboard motor and ran 95 in it and blowers and whipasnipers and a 4 stroke Briggs and Stratton motor on the lawnmower and ran 95 or 98 octain for 90% of the life of the motor and the motor is over 10 years old and going very strong and using 15w 40 oil in it and  never had a problem with them.

  • offroadbob

    Here in America, all 1996 and later vehicles have a knock sensor that retards the spark to prevent detonation if the fuel being used is of lower octane than recommended. In my case, I have a 2001 VW Passat with a 1.8L turbo four that recommends Premium Unleaded (91 octane, the highest available; yes, our petrol is cr*p). However, I have been running it on Regular Unleaded (87 octane) with no perceptible degradation in performance or economy. A number of cars and SUVs sold in the states that call for Premium run fine on Regular during normal driving. Only under demanding conditions where maximum horsepower is needed such as when towing a trailer through steep mountain passes is premium really required, and then ONLY if it says on the fuel cap “Premium Unleaded.” If it is designed for Regular, then, as the author notes, “you will be wasting money.” Of course, this is not true for exotics. While they still have a knock sensor, using anything less that Premium would be, well, senseless.

    • Blitzkrieg

      What price is your gas per gallon over there offroad?

  • half

    Unlikey that E10 would damage a fuel injected car, cos they have metal fuel lines.

    It\’s carburetter cars (and motorcyles) that are affected.

  • WOW

    I own a J31 Maxima it has done 173.000 K on 91 octane ULP.
    That blows the “theory” that running a motor on a lower octane fuel does not damage the motor. If it indeed does damage the motor, it is taking a hell of a long time to do so. Nissan recommends Premium ULP 95 octane.

    I drove a Mondeo diesel “WOW” the worst car ever..maybe a petrol would be better. If I want to drive a vehicle that sounds like a tractor, then I will buy a tractor.

    • WOW

      Correction to my 1st message.

      I own a J31 Maxima it has done 173.000 K on 91 octane ULP.
      That blows the “theory” that running a motor on a lower octane fuel damages the motor. If it indeed does damage the motor, it is taking a hell of a long time to do so. Nissan recommends Premium ULP 95 octane.

      I drove a Mondeo diesel “WOW” the worst car ever..maybe a petrol would be better. If I want to drive a vehicle that sounds like a tractor, then I will buy a tractor.

  • martin

    E10 from United is 95 octane and cheap, so if your car takes ethanol, you get power without pinging – great stuff and not mentioned inthis article.

  • Dman

    Question: When a car manufacturer states a car’s fuel consumption, is that using the car’s recommended octane rating, or the highest available octane fuel?

  • rox

    very informative article thanks for it………………..
    question: i have a holden astra 1996 5 sp manual it has unleaded fuel on the fuel cap flap…..can i use E10 in it if unleaded (standard one) is not available?

  • F1MotoGP

    If 91 octane fuel will be replaced by E10 it is OK long as is not coming from food because “The grain required to fill a 25-gallon (94.6 liter) SUV gas tank with ethanol could feed one person for a year”.

  • Sean

    I had a manaul v6 toyota prado and it used to ping a lot and i used 95 or 98 octain unleaded fuel and the engine ran quiter then on 91 octain unleaded and the toque was a lot better and i got a lot better fuel consumption and i used it for 147,000 km from new and that was with both tanks full and i have used 98 in the lawnmower when cutting heavy grass and it is amazing how much easier  it is on the engine and that is with a 5 hp briggs and strattion side valve engine. I have used 98 octain on 4 stroke outboard motors and the engine runs better up through the rev range to 5500 rpm

  • Abood104

    I have Honda Accord 2.4 2008 clearly I can feel between 95 and 98

  • Sean

    I would like to see ford bring out a turbo diesel ford falcon in all range models with the same v6 diesel as the Tertiary it would make the falcon more inviting for company’s and taxi owners and private buyers and the same with the ute and i’m amazed that the falcon ute doesn’t have a diesel option available. It would help ford Australia. Holden should do the same is to have a v6 turbo diesel commodore option available and in the caprice as well 

  • Ian Graham

    I own a 1970 MG B, it preignite’s something terrible, any suggestion would be appreciated.
    With thanks

  • Clbkeb

    I have a 2005 Mini Cooper s supercharged and was wondering what type of fuel should I use

  • Lunaticmime

    what type of gasoline should i fill my hyundai avante 2007? 90 Octane and 95 Octane?

  • Sandy

    what type of gasoline should i fill my hyundai avante 2007? 90 Octane or 95 Octane?

  • James

    Falcon FG XT N/A runs on RON91, 95 AND 98.
    It makes 195kW/391Nm on RON91, 201kW/409Nm on RON95 and 208kW/422Nm on RON98.

  • James

    Our peugot service dealer tells us that the quality of australian fuel is far inferior to European fuel. Does anyone know if there is any truth in this statement

  • Anonymous

    Well, basically I can’t agree with the article 100% right, although the point is there.
    My car is a 1990 EFi model SOHC engine. It runs only on RON91 octane (Fuel lid mentioned ‘Unleaded fuel only’). I tried use RON98 octane, ended up with engine pinging, exhaust pipe leak due to exhaust back pressure, spark plug need replaced, rough + low idling. All these due to lack of detonation. But when I switch back to RON91, everything seems to improved. I spent so much money on that car repair, ended up just a simple solution : my car cannot perform well on PULP octane petrol…
    So I can’t agree 100% with the article above. Some EFi engines are also sensitive to petrol octane, not just Carby engines.
    I kinda learn my lesson, not every premium petrol are good for old car models, either Carby or EFi

  • milo guy

    what should I be using in my 2004 neo mazda 2 ???

  • John

    I have a 1992 Nissan NXR and have always used 95 octane fuel.My local 7/11 garage does not have 95 anymore but now stocks 91,94 and 98 – does anyone know if 94 takes the place of 95 ?I cannot use 91 in this car. Thanks John.

  • david

    I just put diesel in my 2005 ba falcon ute i run it on unleaded

  • http://britishclassicspareparts.com.au/ Keven Duddy

    Nice article. Not everyone has full understanding of this fuel octane rating. There’s a lot of car owners who don’t even know why there’s this rating and what’s their use. Good thing, articles like this are pubslished to help people.