Cheap(er) petrol...

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570 posts

Ultimate Geek

#1483430 2-Feb-2016 11:53

Best diesel in Wellington is Hutt Road truck stop. (Caltex)

I think it's about 74c at the moment.

Don't need a fuel card ( but I do have one, and save 3c off the pump price) It's just a slight pain as my Mondeo filler is not big enough for the truck pumps, so have to use the one of 2 car ones.

Coil

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#1483431 2-Feb-2016 11:55

myopinion:

996

Early 00's 911 aye. I see a lot of them every day.
my opinion is this or nothing.

kharris

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#1483433 2-Feb-2016 12:00

TimA:

kharris:

MikeB4: Yuck only 91, won't be using it.

What's wrong with 91... most modern engines are tuned for it.

You shouldnt group modern cars by saying "Most"

NZ new cars will say the minimum octane you can use inside the fuel flap.

Never assume. Otherwise you make an "Ass of U and ME"

What assumption? There is no assumption there. Generalisation maybe. It is a statement... most NZ modern engines will run quite happily on 91-octane. I am not assuming all will. 91-octane is not considered low octane... it is however the lowest of the premium octane fuels. 85-Octane is low and is not sold in this country afaik.

Kirk

kharris

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#1483443 2-Feb-2016 12:12

myopinion:

996

Well that is different.... a 996 has a high compression ratio so needs higher octane gas but then it is not your every day run of the mill car.

I am surprised though that it requires 98. In some places in the USA it is very difficult to get anything higher than 93. Maybe Porsche has made modifications to compensate for that market?

Kirk

richms

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#1483445 2-Feb-2016 12:14

US octane is measured totally differently to the rest of the world so cant be compared by numbers

Richard rich.ms

dickytim

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#1483454 2-Feb-2016 12:25

sbiddle:

BTR:

Its amazing the amount of people that don't understand which petrol they should be putting into their cars. I've come across so many people that use 91 because its the cheapest.

Using the wrong fuel can damage your engine and actually give you worse milage than using the correct fuel.

Also theres no point being picky about fuel prices if your tyre pressures aren't correct and your car is full unused items which cause extra weight.

Back on topic fuel in Chch is still around the $1.90 mark and about 95c for diesel.

it's also worth noting that 95 is not subject to the same discounting. In Taranaki for example where you could get 91 for around $1.52 last week it was still around $1.90 for 95

Gull 98 seems to be discounted but BP generally doesn't. The difference there makes using Gull a no brainer as my car can safely run on an ethanol mix.

Next tune it is going to be tuned to better use Gull as the first tune was on BP 98.

Currently in Pukekohe fuel is $167.9 a litre however in Takanini last I looked it was $165.9 with an occasional extra 10c a litre discount from Gull to make my day!

Either way I was paying over $2.50 a litre a while ago so I am happy with where it is at the moment.

kharris

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#1483456 2-Feb-2016 12:28

richms:

US octane is measured totally differently to the rest of the world so cant be compared by numbers

You learn something new every day... I must investigate... thanks.

Kirk

Coil

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#1483457 2-Feb-2016 12:30

kharris:

richms:

US octane is measured totally differently to the rest of the world so cant be compared by numbers

You learn something new every day... I must investigate... thanks.

He beat me to it but yeah, The US has a different scale. we use RON like the EU.

ajobbins

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#1483459 2-Feb-2016 12:32

dickytim: Gull 98 seems to be discounted but BP generally doesn't. The difference there makes using Gull a no brainer as my car can safely run on an ethanol mix.

You're comparing quite different fuels. Also, Ethanol has significantly less energy for a comparable unit than petrol, so any savings at the pump are almost certainly cancelled out (and then some) by the increase in fuel burn you'll have.

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Geektastic

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#1483462 2-Feb-2016 12:33

sbiddle:

ajobbins:

BTR: Its amazing the amount of people that don't understand which petrol they should be putting into their cars. I've come across so many people that use 91 because its the cheapest.

Using the wrong fuel can damage your engine and actually give you worse mileage than using the correct fuel.

While that is true, most cars sold or imported into NZ will work perfectly on 91 (or less) octane fuel, and for those cars, going to a higher octane rating is literally just throwing money away and in fact will result in (ever so) slightly worse mileage.

Only some euro's and high performance cars genuinely need higher octane fuel. Octane rating is about ignition profile and resistance to knock, not about power/energy/cleanness of fuel as many people think. In fact higher the octane, the less 'bang'. Most reasonably modern cars that will 'knock' on lower octane rated fuels will adjust timing to compensate, preventing any damage at the cost of economy. All the ads on TV about getting better mileage on higher octane fuels are really only true if your car is adjusting timing to prevent knock.

Both my old and new Focus both need 95. They both run horribly on 91. In Europe 95 is the standard Fuel so most Euro engines are designed for 95 or greater.

My Land Rover (4.4 Jaguar V8 under the bonnet) says in the manual that 96 is the recommended fuel but that fuel no lower than 91 may be used.

I've never seen it here but in the UK and Germany you could buy 100 octane fuel. I used to buy it sometimes for my Saab Viggen. It was like giving it drugs!

ajobbins

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#1483464 2-Feb-2016 12:36

kharris:

richms:

US octane is measured totally differently to the rest of the world so cant be compared by numbers

You learn something new every day... I must investigate... thanks.

"In most countries, including Australia, New Zealand and all of those in Europe, the "headline" octane rating shown on the pump is the RON, but in Canada, the United States, Brazil, and some other countries, the headline number is the average of the RON and the MON, called the Anti-Knock Index (AKI), and often written on pumps as (R+M)/2). It may also sometimes be called the Posted Octane Number (PON)." Source

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lagbort

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Master Geek

#1483465 2-Feb-2016 12:36

richms:

US octane is measured totally differently to the rest of the world so cant be compared by numbers

Exactly

Octane rating is generally measured as either RON (Research Octane Number) or MON (Motor Octane Number) with slightly varying figures between the two.
Here in NZ, we use RON as our standard rating, the US uses a figure called AKI (Anti Knock Index) which is derived as the average of RON and MON.

In practical terms this means that fuel rated 85-87 Octane in the US is equivalent to 91 here and US rated 93 octane is equivalent to our 98.

Most cars will see no benefit from running an octane rating higher than they were designed for unless they have been modified or re-tuned and in fact it can cause problems with excess carbon build up due to incomplete combustion.

The other one to watch out for are Japanese performance cars from the 90's to early 2000's before flexible fuel mapping was widespread as at the time 'premium' fuel in Japan was ~100 octane RON and many of these cars will have been tuned for it.

My car (2000, Subaru Impreza STi) has to be run on 98 as it has been re-tuned and the mapping setup for 98, this can be a bit of a bother if I go on a long road trip, but generally BP has enough stations along the main highways to avoid too many issues, running a lower octane could result in engine damage.

My bike on the other hand (2014 Hyosung GT650RL) actually likes 91 octane and runs rough on 98.

dickytim

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#1483466 2-Feb-2016 12:38

kharris:

myopinion:

I can only use 98 so only options are BP and Mobil (manufacture says only to use 95 as a last measure). Cant use Gull as it has Ethanol and manufacturer say no to that as well. Prices seem to be much higher with 98 as I was shocked at how much cheaper it was to fill up the wife's massive Commodore tank with 91.

My massive commodore take also likes 91 and the engine is designed to run on it even though it is a 6 litre V8.

91-octane is premium fuel... it is not low octane... other countries sell lower octane fuels (as low as 85)

What do you drive that requires 98?

I have a tuned commodore, which has been tuned on 98 for higher HP from an LS1 (5.7l) it went from 300-odd to 400+ (rolling road so rounding the actual figures) 190RWKW to 240RWKW.

Before my tune I did some back to back comparisons for 6 months and found there was no to very little difference in economy between 91 and 95 and 98 with 98 giving a very slightly poorer ltr/100km.

I have also run a back to back between BP 98 and Gull 98 and found on noticeable difference in economy for the addition of ethanol.

Each test I ran through 4-5 fills and took my average ltr/100km

BTW after my tune to gain more hp I actually increased my mileage and on a good week I can get 11l/100km or if I go out of town down to 10.5l/100km

My methods to increase accuracy was to fill the tank to the brim everytime to ensure I started with the same amount each time.

Your 6litre commodore could be putting down 260RWKW quite easily for around <$5,000 for an exhaust, intake and tune, while returning better economy....You'd be silly not to!

dickytim

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#1483468 2-Feb-2016 12:42

ajobbins:

dickytim: Gull 98 seems to be discounted but BP generally doesn't. The difference there makes using Gull a no brainer as my car can safely run on an ethanol mix.

You're comparing quite different fuels. Also, Ethanol has significantly less energy for a comparable unit than petrol, so any savings at the pump are almost certainly cancelled out (and then some) by the increase in fuel burn you'll have.

I have found otherwise.

When talking about 20c + a litre the increase would have to be significant.

10% ethanol x 50% less efficiency would work out 5% worse at worst (overly simplistic I know as there are other factors) but I have done the sums and am happy to run on Gull.

kharris

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#1483469 2-Feb-2016 12:43

Did you have it re-tuned or was this done by a previous owner. What was the point of this retune? Racing?

lagbort:

richms:

US octane is measured totally differently to the rest of the world so cant be compared by numbers

Exactly

Octane rating is generally measured as either RON (Research Octane Number) or MON (Motor Octane Number) with slightly varying figures between the two.
Here in NZ, we use RON as our standard rating, the US uses a figure called AKI (Anti Knock Index) which is derived as the average of RON and MON.

In practical terms this means that fuel rated 85-87 Octane in the US is equivalent to 91 here and US rated 93 octane is equivalent to our 98.

Most cars will see no benefit from running an octane rating higher than they were designed for unless they have been modified or re-tuned and in fact it can cause problems with excess carbon build up due to incomplete combustion.

The other one to watch out for are Japanese performance cars from the 90's to early 2000's before flexible fuel mapping was widespread as at the time 'premium' fuel in Japan was ~100 octane RON and many of these cars will have been tuned for it.

My car (2000, Subaru Impreza STi) has to be run on 98 as it has been re-tuned and the mapping setup for 98, this can be a bit of a bother if I go on a long road trip, but generally BP has enough stations along the main highways to avoid too many issues, running a lower octane could result in engine damage.

My bike on the other hand (2014 Hyosung GT650RL) actually likes 91 octane and runs rough on 98.

Kirk

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