What petrol do you use?

[jjs 60]

Just filled up the car last night at BP using Ultimate. Cost over $100...

Which got me thinking, is this high octane unleaded really worth it?

I have heard from several people that the high octane stuff is much better for your car and because the octane is higher, the car uses less (so the cost of running works out to be the same). Is this true?

What are your thoughts?

[Yuen 16]

I usually go with 95 at Shell just because I can save some $ from using the fuel vouchers I get from shopping. But if I had a choice, I'd go with BP 98 - people have told me that they do get a little more mileage from 98. Personally haven't used it enough to make a conclusion.

[tire 10]

I just bought a new 1986 318i and gave it 91 unleaded... was that the right thing to do? I notice i gets quite hot...

I get it from shell/gull cause we shop at woolies an get a 6c per litre discount.

Edited October 27, 2007 by tire

[tibbs.james 1]

I normally use caltex 95, never tried 98 because one time i used a bottle of octane boost forumula ( cost $15 ) and put it with the 95 and it made no diffierence at all.

[Yuen 16]

I just bought a new 1997 318i and gave it 91 unleaded... was that the right thing to do? I notice i gets quite hot...

I get it from shell/gull cause we shop at woolies an get a 6c per litre discount.

On the E36 320i 91 causes a noticeable loss in power - minimum I go with is 95.

[muppet23 0]

I have been using 98 and have noticed an improvement in economy over 95, no power difference noticed though. I use the discount vouchers for BP from New World so it doesn't make it to much more expensive.

[cainchapman 0]

There is definitely a performance increase (and in theory, an economy return from the lower throttle percentage needed for the same performance with a lower octane)

Dyno'd the car with 95RON 165kW at the wheels, and again (on the same dyno) with 98RON and had 173kW at the wheels.

Milk is still more expensive.

[bmw.maniac 1]

I use 95, only because it's the highest octane you can get on the Coromandel. I shop at Caltex, but would buy from Shell if we had one here.

Edited October 22, 2007 by Eddy

[ThreeOneEight 0]

98 from BP. I get 16 cents a litre off from New World shopping so it's pretty reasonable.

[tire 10]

98 from BP. I get 16 cents a litre off from New World shopping so it's pretty reasonable.

16 cents or 6? Cause 16 is some epic savings.

[m_power 0]

I use either 98 at BP, but usually they are always first to put there prices up and last to put them down so i go to Shell and use 95.

[hybrid 1039]

98 BP ... mobil have issues with there tanks and have found the car will generally pink with mobil in it.

Never had an issue with BP Ultimate.

Octane booster doesn't do anything BTW you really need to have "off" fuel for it to make an difference ..

Here is an interesting video for you all..

also for interest

http://www.liveleak.com/view?i=73e_1192001762

[M325is 0]

I use Gull 96 only cos its the only petrol station about. Otherwsie every second week I get 98 from BP with my 10c off a litre voucher from new world. I get an extra 25miles off 98 so id say it works out the same.

[kiwi535 538]

my owners manual says 91 so thats what i use.....never noticed any pinking.No performance difference using 95(96) or 98 but the car feels a bit smoother ,and I get marginally better economy .No point using higher octane with any older than mid nineties because without knock sensors the ecu cant adjust the timing to take advantage of higher octane.Similarly dont use any thing lower than recomended.in a old engine cause the engine cant compensate for pinking either.

[tire 10]

Whats pinking?

[kiwi535 538]

pinking is a term to describe detonation or preignition.its is heard as a rattle coinciding with application of the throttle at lowish revs,ie climbing a hill or smetimes as you take off.

[tire 10]

Oh I hear cars doing that all the time.

[bravo 34]

96 at BP because we don't get 98 up here, BP is the closest gassy, and I use the discount vouchers from New World plus AA points (nearly get free AA membership).

Use 98 when in Auckland as still go to BP out of habit and most only have 98.

$ per mile on 98 is same as 95/96 as economy slightly beter. No noticeable power increase.

[my_e36 43]

Usually 95/96 in normal cars but use 98 in the old Mini ($30 a tank to the brim) which starts easier and run smoother.

Hardly uses 91 these days and I don't miss those black stuff at the exhaust that doesn't appear when using 95/6/8.

[hotwire 352]

my owners manual says 91 so thats what i use.....never noticed any pinking.No performance difference using 95(96) or 98 but the car feels a bit smoother ,and I get marginally better economy .No point using higher octane with any older than mid nineties because without knock sensors the ecu cant adjust the timing to take advantage of higher octane.Similarly dont use any thing lower than recomended.in a old engine cause the engine cant compensate for pinking either.

Not entirly true regarding high octane for pre mid nineties - Used to have an Audi Quattro (86) which we had when leaded fuel was still around, ran fine on the old 96 leaded. Once lead was removed the car was almost undriveable on the new 95 without pinking - particually on hot days where the engine temp would go to nearly 100deg in traffic. Nothing wrong with engine/ign timing. Tried av gas & it ran like a clock. Engine was factory 10.5 compression ratio. Had the same problem with all 4 main fuel suppliers. We had a local Challenge station at the time with which the car would be OK (theirs was a true 95 octane) but still not as it should have been - vehicle specs were for 98 which it obviously needed.

Similarly our old 1978 E12 with M20 engine is specified in its manual to run on 98. Being a bit of a slug, the difference can certainly be noticed in that car between low & high octane fuels although being auto it is not inclined to pink.

Knock sensors in modern engines will only allow for retardation of a base timing for lesser fuels - not advancing from base for higher fuel

[alex 0]

98 BP ... mobil have issues with there tanks and have found the car will generally pink with mobil in it.

WTF !@#@&*

Last time i go to Mobil Taka.. I'll try BP Lake Road.

Thanks Hybrid.

I'm usually 98 Mobil.. not for much longer.

[jjs 60]

Wow it is interesting to see BP really dominates here!

Apart from the fuel discount vouchers, is there is another reason for this?

[hybrid 1039]

It seems to have something to do with the either the time mobil lets their petrol sit and / or the water table in the tanks. This may not be the same for every mobil but the ones in AKL I have tried just seem to be inconsistant where as BP I have never had a problem.

Around the older car side of things... you probably wont notice the difference as much as fuel injection technology has changed over time. "Atomisation" of the fuel is a lot better in newer cars as the injectors will break up other fuel a lot better.

Pinking is caused by a lot of things.

* worn spark plugs / HT leads

* h2o in the fuel

* ambient air temprature too high

* worn injectors

* high humidity

* low octane ratings (NZ's bad fuel) (NZ rates fuel in RON not PON like the U.S )

* blocked air filter

* buggered AFM

* abnormal lower compression

you get the picture....

here is an explanation I posted last time

http://www.bimmersport.co.nz/forums/index....st=0#entry77464

[MADBMA 0]

im using shell 95 at the mo just to get the ferrari cars used to use bp 98 but found that the extra cost didnt really make it worthwhile so gone back to 95/96 dont mind to much where i get it from but im another one that doesnt like mobil.

[hybrid 1039]

I took a drive recently from AKL to wellington and back (all between 24hours)

I noticed the difference when 95 started to head into the lines vs the 98. the car was a bit more sluggish mainly in the mid range area.

But was all good once I got 98 back through the tank / lines. (took a couple of fills)

It does only make the slightest of difference. Maybe the difference you feel between a cold and hot day.

On the higher compression motors you defantinly notice it. (EG M3)

I guess, its for the driver to decide weather the difference in their car is worth the money or not. 95 is fine for most people.