[danielt]

Just wondering what car and what octane number you use?

I'll definately be avoiding 91, but there's some debate whether 95 or 98 or 100 with 5% ethanol is the way to go

is a particular choice more critical with turbo'd engines VS naturally aspirated ones?

Thanks.

Depends on your engine.

I put 95 octane in my 320i at Xmas (no 98 available for a week) and it was TERRIBLE! My old Ford Escort felt faster. I hated hated hated it. 98 made a massive difference.

As for 6 cylinders, 95 won't make a huge dent as you have the power reserve. Bear in mind that you get better economy with 98 (yes, really) and it is better for your engine, so 95 doesn't save you much...

If you're buying a 335i then $4 or $5 a week shouldn't matter ;-)

[astra]

i put 95 in my 325 vert most of the time, but ocasionally i put in 98, and ot be honest, it doesn't make much difference, but does make some

Yeah, I have to agree. I used 95 and 98 in my old 325Ci and it felt almost the same.

My conclusion:

4 cylinder = 98 octane a must
6 cylinder = 95 octane or higher a must...

[chem0]

330ci

98 octane (Vpower or Vortex98)

if shes been a good girl then the occasional treat 100 octane (Vpower Racing aka Optimax Extreme)

Out of interest how much more is 100 octane over 98 octane?

Last time I checked, 98 is about 10c more than 95 per L - is 100 another 10c per L on top of 98?

[astra]

i have only ever seen 100 octane at 1 servo

[1q2w3e4r]

98 RON in all of them. I'll be retuning the GTR for 100 RON fuel when the local Shell goes to Extreme.

For most cars your not going to notice a marginal difference at all. My E46 M states that it will run fine on 95 RON, but is recommended for 98. The difference between 98 and 100 RON isn't worthwhile unless you have a performance engine that preferably has an engine management system tuned to get the most out of it.

Your better off saving your money with most BMW's than running 100 RON through it, it's just costing you extra for no reason IMO.

[eml]

m3 has only had 98 so far

[LEA69]

BP Ultimate!!!! 98!

[LEA69]

Only 'cos my sister works for Shell!!!

[aem]

Sports car gets better performance from high RONs, aint got nothing to do with whether it is 4 or a 6.

For me i only use the best. My car recommended 95, i used 98 but will not mind 100 if i see it.

[1q2w3e4r]

Originally Posted by aem

Sports car gets better performance from high RONs, aint got nothing to do with whether it is 4 or a 6.

For me i only use the best. My car recommended 95, i used 98 but will not mind 100 if i see it.

It's a waste of money using 100 RON unless you retune the ECU to get the best out of it. With a car that has FI the advantages are obvious, not so much so for your run of the mill BMW's or NA cars. But, it's your money.

[astra]

Originally Posted by 1q2w3e4r

It's a waste of money using 100 RON unless you retune the ECU to get the best out of it. With a car that has FI the advantages are obvious, not so much so for your run of the mill BMW's or NA cars. But, it's your money.

presicely my friend

[aem]

Originally Posted by astra

presicely my friend

Not quite but that's another discussion altogether.

During my old days of owning a civic, using PULP pretrol does wonders over normal ULP (recommend for the civic), one thing I notice was the PULP gives me more milage than ULP. And I did not alter the ecu.

[moO moO nEL]

Shell Optimax 100 is now called the Shell V-Power Racing fuel.

[1q2w3e4r]

Originally Posted by aem

Not quite but that's another discussion altogether.

During my old days of owning a civic, using PULP pretrol does wonders over normal ULP (recommend for the civic), one thing I notice was the PULP gives me more milage than ULP. And I did not alter the ecu.

Yeah, explain as Porsche, BMW, Mercedes, Audi etc tune all their high end models to run on 95-98 RON fuel. To get the most out of 100 RON fuel you have to tune the ECU while running 100 RON fuel.

[astra]

Originally Posted by aem

Not quite but that's another discussion altogether.

During my old days of owning a civic, using PULP pretrol does wonders over normal ULP (recommend for the civic), one thing I notice was the PULP gives me more milage than ULP. And I did not alter the ecu.

i am not surprised a civic got a boost from a 98oct..

Well, according to BMW driver training, high performance cars are rarely used anywhere near their potential on public roads (I can vouch for that after a hot lap around Eastern Creek in the M3).

IMHO the octane makes more difference in day to day driving for those with less power.

I know it's slightly off topic, but I'd argue that the weather has FAR more effect on engine performance than octane.

Drive a 320 in Winter on a nice 15C day and then compare its performance to being driven on a 30C humid Summer day....The Winter drive is like putting 150 octane in it LOL

And for you 320 owners out there, only put 95 octane in if you are desparate...myself and a mate put it in ours and they run like absolute dogs - I even had trouble keeping up with a Hyundai Excel

[aem]

Originally Posted by astra

i am not surprised a civic got a boost from a 98oct..

It wasn't a normal civic, nor was it one done up but it could kick the 320 any day and night. Don't knock cars you don't know much about not that i'm saying you are in this instance, but that's FYI only.

As for the Excel, it would be a real shame if a car costing 10x more than it cannot keep up with it. I would not be looking at fuel in this case but rather a swap.

[astra]

wtf does an excell have to do with the price of eggs? that was a bit random...

Originally Posted by astra

wtf does an excell have to do with the price of eggs? that was a bit random...

320i 95 Octane - can barely even keep up with an Excel
320i 98 Octane - Doesn't run too badly