chrisp

MrProdrive, prodrive put figures out for NUL and SUL for their PPP so yes it does affect performance and give more bhp, smooth running and MPG. I cant believe people still dont use good fuel LOL

[Edited by chrisp - 9/2/2002 12:34:10 PM]

ProperCharlie

here are the results of my research so far:

Fuel Litres Gallons Miles MPG
Optimax 48.33 10.631 195.0 18.34
Optimax 44.06 9.692 188.5 19.45
Optimax 43.90 9.657 180.9 18.73
BP SUL 52.82 11.619 225.6 19.42
BP SUL 47.47 10.442 199.9 19.14
BP SUL 48.04 10.567 226.5 21.43
Tex SUL 52.53 11.555 223.9 19.38
Optimax 52.97 11.652 208.2 17.87

AFAICS Optimax seems to give slightly lower MPG, but I'm still using it.

Charlie

[Edited by ProperCharlie - 9/2/2002 12:51:31 PM]

mrprodrive

does it really matter and how does it effect performance ?
i try and use super all the time, but seems to be a shortage of garages in aberdeen that has it.
also new shell optimax, whats that all about ?

HKSubaru

everyone uses shell optimax!
but if it's hard to get then just go for super unleaded. people prefer cars to run with optimax, as it's the closest thing to the 100 ion they use in japan.

gareth

Reluctant to start this off again, but I thought that Optimax was found to be no more than "modified 95RON"... I've gone back to using SUL (as my PPP ECU is theoretically tuned for 97RON) and find it superior. Occasionally run a tank of Optimax but just to get the benefit of the built-in cleaners...

G

HKSubaru

you buy a nice car so you might as well run it with good fuel.

northernmadbugger

Is it worth having the ECU mapped specfically to Optimax ??

I have historically ran normal followed by Super now onto Optimax fuel - do alot of travel throughout the UK and find specific garages (decent petrol) hard to come by.

I am now a firm believer of optimax and have started using now constantly - have got a breakdown of UK shell petrol stations )

ash1

iTrader: (2)

Found the P1 loved SUL and not so Optimax (stutters a bit on Optimax) and performance is best with SUL

gareth

I think it's a Prodrive thing...

Makalu

My MY01 PPP loves Optimax (ECU was reset when using it)... Notable difference.

Mak.

BKS

Gone off otimax. Reckon i had a bad batch that have degraded. Now using BP SUL (98) RON then at least i know what i am getting!!

gareth

Don't think that BP is 98RON, but apart from that I know what you mean. Predictability isn't such a a bad thing.

BKS

swear to god. BP garage northenden has 98 RON SUL. Found it yesterday by mistake. 81.9p a litre though!

boomer

Just because the BP pump says 98RON, it doesn't mean that the fuel is!!

I would suggest that you ask the garage to confirm the RONnage, and if they still say 98 then get it checked.

SUL dropped to 97 a few years ago

mb

BKS

dont be such a cynic boomer i asked the garage and they confirmed it was 98!! I would test it but i left my pocket petroleum plant at home!

Type_RA

Boomer is quite correct because SUL a small volume fuel it was dropped from 98 to 97 RON. The reason being that leaded fuel was banned. The meant they produced LRP which was 97 RON to replace it, SUL has the same base as LRP but has a different set of additives. I maybe wrong but why would they make, 95 UL, 97 RON LRP and 98 RON SUL but BP maybe different like Shell and produce a higher RON fuel. The LRP and SUL are very low volume compared to UL. Also every main stream car in the UK from 1992 onwards had to have a cat so had to use NUL at least ie LRP would be useless in cars post 1992. A lot of cars pre 1992 could run on unleaded as well so the demand for LRP must be getting less each year.

Also the Optimax rumours, its at least 98+RON and according to Shell it takes years to degrade and hasnt been out years . My RA loves the stuff so if you wont buy it I will .

Personally I would be more worried about buying degraded SUL as most people know about optimax so the tanks must have a bigger turnover.

[Edited by Type_RA - 9/2/2002 7:49:34 PM]

[Edited by Type_RA - 9/2/2002 7:51:18 PM]

BKS

mmmmmmm......

greengilbert

just got scooby 3 month ago.dealer said unleaded ok as it makes no difference using super unleaded.please tell me if he was wrong

Type_RA

Basically all turbo impreza run an adaptive ECU. The ECU depending on what fuel you use, sets the advance and retard on the ignition. If you run better fuel the car can potentially run more ignition advance which it turn may mean smoother running better mpg and more power/torque.

A standard unmodfied UK can quite happily run on NUL but my UK dealer when I had my UK turbo told me to run SUL all the time if I could find it as the car would perform better. I personally wouldnt run any turbo impreza on NUL given the choice.

cheers

BKS

:eek dealer is talking sh1te. honestly, IMHO it does make a massive difference. dont think i would ever run my car on anything less than super.

bug-eyed wonder

Definative improvement on SUL. Wouldn't use anything else.

Riftzone

After being told by my dealer to run NUL, did so for the first 10 tanks. Now on my second tank of SUL and cant really see a difference in performance or smoothness.

Gonna do a 10 tank comparison for SUL and then switch back to NUL to see if I see a degradation (MY99 UK turbo). The jury's still out here...

Btw, someone said there are quoted PPP bhp for NUL and SUL - wot are they ? Presumably this same difference will apply to a standard UK car ?

gareth

My MY99 was noticeably smoother picking up on SUL than on NUL, though ultimately no faster.

I remember seeing the PPP NUL vs SUL figures in the UK300 literature. Can't remember the NUL bhp exactly - somewhere in the 230s I think. The quoted UK300 SUL bhp is 246. I assume the same figure applies to my MY01 with PPP.

You won't get 10+bhp extra from a non-PPP car just by using SUL. The point is that Prodrive set up the PPP ECU specifically to take advantage of SUL.

G

chrisp

The figures that seem to stick in my mind for the PPP are 240 for NUL and 245 for SUL but as I dont have a PPPed car I maybe wrong.

Boost II

iTrader: (1)

I used to use normal unleaded all the time - never saw any improved performance, smoothness or mpg with super unleaded. Then i tried Optimax....it is all I ever put in now. You can feel more power/better response.

TolTec

Even my wifes Rover 216 auto feels better on Optimax, I would only put NUL in my turbo if I was desperate for fuel. Have not tried SUL as I have a Shell on the way to work so no need to.

fandango

Have not found a power difference using optimax but there is less turbo lag so picks up quicker.