chrisp

Your car has an adaptive ECU which detects the knock of the fuel. The ECU then adjusts the ignition advance and retard. Running a higher RON fuel and the ECU will give you more ignition advance. So it should be smoother, more powerful and even may get more mpg .

Cheers

Chris

[Edited by chrisp - 11/2/2002 9:57:52 AM]

gareth60

Difference no, but to be fair I was running in so I kept it below 4000 rpm. I was told that because it's an Sti, even though it is a uk spec one, it is designed to run on Super.

Ps. Rifezone, impressed by your speadsheet!!

[Edited by gareth60 - 11/6/2002 9:05:09 PM]

Imp Jay

hi all
had a my00 now for 3 months now, still takes me 2 hours to go to the corner shop,!!!
brilliant cars
i run the car on n.unleaded most of the time due to travelling, its totally standard & uk spec,runs fine
but is it safe, as i read you all use superunleaded or optimax
& will it lead to engine damage!!
i would be grateful for any info

uneducated scooby owner .

ash1

iTrader: (2)

NUL is okay for emergencies, but I do recommend Super, I use it in the P1 and its like a totally different experience. Also, Optimax is good too, but my own preference is for SUL - but then I think the P1 is mapped for it !

SUL costs more, but I tend to get more MPG so it works out pretty even.

oh, and welcome to the forum.....

Imp Jay

thanks ash1
for the reply

better use super then & tell the wife.

Brun

I gained more mpg from using SUL. Even though it costs more to fill up, i do actually save between £1.50 and £1.70 per tank. Can't say i've noticed any power gain but it is much smoother

gareth60

I had to put Normal unleaded in my Sti7 last night as I was completely empty. I only put £10 in just to get me home. I normally run on Super.

The Esso station I stopped at in Lakeside really pi55ed me off. Not only did it not have any super, only two pumps were working and they were on the wrong side... arrrr...

Gareth

The TunnelMeister

Agree with the mpg comments, I seem to get slightly more on SUL as well. (P1)

TTM

Daddy-P

Having run my MY99 4-door Turbo on normal unleaded since I picked it up last week, the tank is almost on empty. Can i put SUL in on top of the last few drops of NUL?

The TunnelMeister

D-P,

Yep, just fill it up!!
Will take a little while for ECU to adapt but you should feel a difference once it does.

Imprezive

HI, welcome to the collective!, i usually run on optimax,
seems smother than the n/ul, enjoy your scoob, it will
pass most things exept optimax pumps,.

B

Daddy-P

Thanks TM - another dumb newbie question but what exactly is Optimax? I was assuming it was a fuel additive, but from the last post it would seem I'm mistaken.

hades

Optimax is Shell's high octane fuel, IIRC officially 98.6 RON - they sell it rather than super unleaded, sometimes at better price than super too. It's more like normal unleaded with octane boost rather than super unleaded, I'm told. There has been a lot of optimax vs super unleaded threads.

The TunnelMeister

D-P, see above!

I'm very happy running Optimax in my P1, especially with a good Octane Booster

I don't get the same 'feel' of urgency with SUL.

TTM

The TunnelMeister

Sorry D-P, Octane Booster's can take the Octane rating of fuel up by 2 - 3 points? Therefore Optimax & a good Octane Booster = ~100 RON.

Imports/Import based Scoob's were originally designed to run this fuel. (I believe it's all they have in Japan! - poor things!)

Works well for UK car's too!

TTM

STi-Frenchie

LOL ! Funny you should say that, I just nipped out to get some ham and cheese from the shop about 1km away.

Took me an hour and a half

Welcome to the club !

shoppe

hi have you put in q8 sul.i did and it does go better than other sul,octane is 98.
shoppe

Mike Owen

Always an interesting one, this....

Tried SUL in both my previous two Scoobs (MY97/99) and after a couple of months, went back to NUL. Must be honest, could not notice any difference and as to the extra MPG, this is such a difficult one to "really" quantify. Even if you do a lot of very similar long distance journeys (IE. Dumfies-Edinburgh-Perth and back every week in my case). My current UK WRX, I moved over to Optimax for four months and have just gone back to NUL (couple of weeks ago). The only difference is that it "maybe" "at times" feels a bit smoother when it was running on Optimax. I was always under the impression that the UK cars were set up to run on 95 RON fuel. So the "exta" from a higher octane rated fuel is at best going to be minimal. Well that's my theory.

Really up to the individual. Though the folks with P1's and Imports are obviously in a different position.

O'hum... just wish the face lifted WRX had been given a bit more grunt. Slightly off topic, but never the less, a bit disappointed.

Enjoy your cars...............

chrisp

I had an MY98 and the dealer told me to use SUL all the itme. Yes UKs will run on 95 as the map is intended to retard that much but the lower the fuel the lower the ignition advance and ultimately the lower the power output. It has been shown that low RON fuel gives lower peak boost. Its your car and your money and upto you what fuel you run in it .

Daddy-P

Another dumb question, but I was told yesterday that "supermarket petrol is the scourge of all performance cars"!!! Is this right? Is there any reason why I should choose BP SUL over Sainsbury's?

LB4

I have a Uk MY00 and it says on the inside of the petrol flap, "use super unleaded only" .. in about 4 languages .... so i definatley wouldn't run on normal unleaded unless absolutely essential and even then only enough to get to next station and stay off boost.
I usually run Optimax but as the nearest Shell is 10 miles in either direction!!!.... i have started to use Esso Super a bit more lately.

scoobyfella

I also have a MY00 (January model classic) and my dealer told me only Nul (this is normal unleaded i pressume) so i can put in optimax deffinetly without damaging the engine, just want to give it a try.

James

Daddy-P

But what about Sainsbury's SUL? Is it OK???

markbluemica

scoobyfella i also have a my00 and have only ever run optimax or svl it does make the car run smoother and will be better for your engine the only thing ive noticed about optimax is if the car stands for a while optimax seems to degrade a little.



mark

scoobyfella

Hi Mark,

And yours is a classic as well i presume, Well i think i will give it a try next fill up, funny how dealer told me to only put in unleaded though.

Thanks Mark,

James

Riftzone

its another petrol thread

inside flap on my MY99 says super, back of the owners manual says 95 ron. UK cars can run both without problem. read the sidc faq - super unleaded in some countries means 95 ron, yet in the UK normal unleaded is 95 ron and super is 97 or 98 (dependin which brand).

personally i see no performance gain with super and actually get less mpg so have switched back to normal unleaded after a good trial. results here:-

http://www.riftzone.fsnet.co.uk/scoobown.xls

gareth60

I got totally flamed when I said I was running my Sti7 Uk on normal unleaded only. Must admit, since then, i've always used Super or optimax.

Gareth

Riftzone

noticed any difference gareth ? i sure as hell havent...

STi-Frenchie

I've been told that under no circumstances whatsoever should I run my (euro) STi on anything less than Super Unleaded/Sans Plomb 98...heard it from the dealer, heard it from the main agent, says it in the manual, says it on the inside of the fuel door, and I'll prolly hear it on my upcoming Subaru track outing. I still double and triple check it at the pump to make sure the right stuff goes in.

Bottom line is that I don't know what performance might be like on 95 with or without octane boost but I've been told that I run the risk of damaging the engine if I use anything less than 98. Ergo, I won't and will have to just live with 98 until 100 comes in.

Can't complain with the beast unleashed on 98, well, apart from a heavy thirst !

Riftzone

cheers gareth. done as scientifically as possible on the very same 35 mile round trip to work, with same drivin style, fillin up at the same pump.

from the bible (sidc faq):-

"In the UK, the standard (or premium) unleaded fuel is rated at 95 RON, the same as the Super available in other countries such as Australia and the US.

Generally, in the UK, normal unleaded is fine. In countries where lower quality fuel is available, then the best advise would be to run on the Super (or Premium) Unleaded fuel.

Some owners report gradual improvements by simply running on the higher spec fuel, but most will find that although it is not any faster: the engine will be slightly smoother and the economy increased marginally (by about 5%). This subjective improvement can be hard to justify against the premium in fuel price."