What petrol to use

[skubez 0]

Hi all

I still haven't taken delivery of my new BMW yet, this is happening on Sunday (woohoo ), but was kinda wondering what gas I should be using for my long drive from Wellington to Auckland. I really don't want to go all that way on the wrong gas and stuff anything up.

What are you guys/girls using? What is the car supposed to run on?

I have heard that all n/a cars should run fine on 91, but then I have also heard that older cars may not, and should run on 96?

[Grant 4]

Definately, run it on Premium Unleaded. Either 96 (normal premium) or 98 (BP Ultimate or Mobil Synergy 8000).

You won't hurt it running 91, but it will behave itself better on 96.

Remember that in NZ, we have crappy petrol, and our our octane ratings are not very accurate...i.e. i think that 91 is really 87 octane, so is just 91 in name only.

Cheers

[Guest MSBOND]

My car runs great on 91, no need to pay more.

[Guest MSBOND]

unless your running a later then 1990 or its a performance car theres no point in using higher then 91, if you think it works better im guessing its all in your head, geese its a 318i, maybe a 325i.

[Grant 4]

Shelly

Do you realise that even though you are paying more per litre for 96, you actually end up paying less per km.

96 burns much more efficiently, and you will get much better fuel milage and economy out of using 96 than 91, especially when the engine is designed to run on that octane.

Cheers

[*sic 1]

my dirty ol honda, came from factory wanting to be run on 100+ octane.. so yea it loves getting close to it on 98.....

or avgas

[Guest Andrew]

unless your running a later then 1990 or its a performance car theres no point in using higher then 91, if you think it works better im guessing its all in your head, geese its a 318i, maybe a 325i.

You can get more power out of 98 shelley, the 318i we have runs way advanced timing and goes so much harder than yours.

Its not a matter of a performance car or not its a thing to reduce knock and pinking and perhaps fuel economy. Look in your owner manuals it says minimum 96 RON.

Grant are you sure your not confusing our RON index with AKI index? 87 AKI = 98 RON here.

[Guest MSBOND]

I ran 96 wen i first got it and i found no difrence wen i changed to 91, im happy with it.

[E30_318i 0]

I run on 96, never tried 91 so wouldn't know if theres a difference.

A few months ago, NZ Autocar did a dyno with a Hyundai Tuburon between the two, and found 96 gave (off the top of my head) 7 more kw and 15 more nm, and concluded that people thinking they are saving by buying 91 actually aren't, as they will need to use more gas to compensate for the power loss (that is pretty obvious when you think about it, but I'm sure most people haven't thought of that).

[Guest MSBOND]

Petrols so expensive thooooooooooooooooo, the difrences wod be a 4 pack of jimmys.

[Guest Andrew]

I ran 96 wen i first got it and i found no difrence wen i changed to 91, im happy with it.

perhaps you should advance the timing a bit on 96/98 and see how it goes then.

[Napier_E36 0]

i did notice that when i ran my car on the 98 up in auckland - it runs smoother and it has more power and all that - they need to get 98 availible in Napier - I know a lot of people that would go out of their way to get some a!! we do every time we go to a town that has the higher octanes...

[Dnz 0]

so if only bp and mobil got it.. - how much does it cost compared to 96 at shell?

I may change where i go then..

[Napier_E36 0]

so if only bp and mobil got it.. - how much does it cost compared to 96 at shell?

I may change where i go then..

it is only a couple of cents more expensive than normal 96 - well worth the money is how i found it!

[Viking 0]

I run 96 on mine, found the performance to be quite nice and the economy is also quite good (around 360-400km to 30L) thats spirited driving too, so I could do better. Havent found a easily available source for 98 yet down here but wouldnt mind trying it.

[skubez 0]

Cheers guys.

Well, I have finally got my new (old) BMW. I found that it isn't that much more economic on gas than my WRX, but it might be cos I've been trying to ring it out a bit. I haven't filled it up yet, but I will try to run it on 91 to start with and then switch to see how it goes. I will probably end up running 96 just for the added performance factor even though it costs a bit more.

[skubez 0]

I have a sneaky suspicion that someone may have modded up my 318i, it uses quite a lot more gas than I expected a N/A car to use (especially one with EFi - someone please let me know if it doesn't have EFi!!) and the other thing that alerted me to mods was the odd whining noise near the rear of the car that sounds similar to aftermarket fuel pumps. It also has a pod filter, MOMO gear knob etc so someone may have been tinkering around with it at some point.

Is there anyway I can check whether this car has EFi?

My sister drove the car from Wellington to Taupo for me at the weekend and it used 3/4's of a tank to get there. Does anyone know if this would be a normal amount - and my sister doesn't drive hard by the way.

[E30_318i 0]

My sister drove the car from Wellington to Taupo for me at the weekend and it used 3/4's of a tank to get there. Does anyone know if this would be a normal amount - and my sister doesn't drive hard by the way.

Ouch. I can get my dads Maxima to Hamilton from Wellington on 3/4 tank, umm, around a 65L tank I think, never tried it in my 318 yet, but I'd put money down on it been much less. Edited February 23, 2004 by E30_318i

[Grant 4]

your car is definately fuel injected.

The E30 318i is supossed to get about 11km/l (26mpg).

Therefore on a full tank of gas (assuming you have the 64 litre tank) you should get about 700km's on a tank.

Wellington to Taupo is about 370km's, therefore you should use 33 litres of petrol (just over 1/2 a tank).

It would seem you are using a bit more petrol than you should, but remember it may be the fuel guage being a bit inaccurate. When mine is sitting on empty, I still have about 14 litres left in the tank (which is effectively 1/5 of a tank).

Hope this is useful.

Cheers

[skubez 0]

Cheers Grant

I need to get the car serviced anyways as it runs rough and stalls just after you turn it on. I have to hold the throttle in (on about 1500rpm) for about 20 secs to stop it from stalling. It probably just needs a good oil change etc. Hopefully it will run a little better after that.

Cheers for all the replies by the way. You guys (and girls ) have been really helpful.

[Guest Andrew]

Cheers Grant

I need to get the car serviced anyways as it runs rough and stalls just after you turn it on. I have to hold the throttle in (on about 1500rpm) for about 20 secs to stop it from stalling. It probably just needs a good oil change etc. Hopefully it will run a little better after that.

Cheers for all the replies by the way. You guys (and girls ) have been really helpful.

all m10 powered 318s do this.. its odd. Get the timing checked.

[Guest hizza bizza]

odd whining noise near the rear of the car

I take it your diff isin't buggered?

[*sic 1]

whining...hmm well you can always rip out your fuel pump and check if its after market.. maybe you got high flow rails too ... jk

i personally never heard any whining from them aye

[lowbm 0]

I run my car on BP ultimate 98 octane. But not all Bp stations have it.? luckily i ownly fill up apprx every 3 months.

(garaged)

[Guest Speedye30]

Sounds like everyone has got an opinion about this... hmm won't bore you with mine.

Here is a short excerpt from a very well researched and referenced paper converted to html:

What happens if I use the wrong octane fuel?

If you use a fuel with an octane rating below the requirement of the engine, the management system may move the engine settings into an area of less efficient combustion, resulting in reduced power and reduced fuel economy. You will be losing both money and driveability. If you use a fuel with an octane rating higher than what the engine can use, you are just wasting money by paying for octane that you can not utilise. Forget the stories about higher octanes having superior additive packages - they do not. If your vehicle does not have a knock sensor, then using an octane significantly below the requirement means that the little men with hammers will gleefully pummel your engine to pieces.

You should initially be guided by the vehicle manufacturer's recommendations, however you can experiment, as the variations in vehicle tolerances can mean that Octane Number Requirement for a given vehicle model can range over 6 Octane Numbers. Caution should be used, and remember to compensate if the conditions change, such as carrying more people or driving in different ambient conditions. You can often reduce the octane of the fuel you use in winter because the temperature decrease and possible humidity changes may significantly reduce the octane requirement of the engine.

Use the octane that provides cost-effective driveability and performance, using anything more is waste of money, and anything less could result in an unscheduled, expensive visit to your mechanic.

Want to know more? FAQ: Automotive Gasoline Hah you'll be reading all night!