virgin

Full de cat and P.E induction kit, was running 98 ron optimax for a few months, just put in 97 ron superunleaded and unless i am losseing my marbles,the car runs better ! ,it feels like it has a bit more power.

Am i bloddy nuts or could there be a technical explanation for this ?

dhorwich

optimax can degrade apparantly..!! i.e if its sat in your local petrol station tank for weeks...

Dan

stephen emery

what u got as a motor m8?

virgin

2000 wagon uk turbo

greasemonkey

The octane rating of any petrol will degrade over time Dan. Whether Opti degrades quicker than other brands of fuel may be something worth investigating however.

Virgin, it is unlikely that changing from Opti (unless the Opti you were using has been sat in the tank for weeks), to SUL would alone be responsible for an instantly noticeable difference in performance.

Two things are possible here. Firstly that your mind is playing tricks with you (), and there's no real difference at all.

The second possibility is that something else is responsible for the difference in performance. Could simply be that the recent colder weather is making yoour car work better, or it could be that your MAF sensor is underreading and making your car run leaner than it should do under WOT.

If the latter is the case it's worth keeping an eye out for other symptoms - particularly dodgy idle, as you don't want a failing MAF sensor on there any longer than necessary.

chrisp

optimax thread - the reply

http://www.scoobynet.co.uk/bbs/threa...hreadID=168419

chrisp

actually more likely to be the weather I got a great charged effect this morning. The car seemed to revs effortlessly.

Glenn_R

Virgin, glad I'm not the only one who thinks their car runs better on SUL than Optimax. I keep trying Optimax for a few tankfulls throughout the year but always go back to 97 SUL as the car always feels it is running smoother and a bit quicker

Either that or we're both ready for the Loon Farm!!

minister of speed

Yep.

MY02 WRX wagon - deffo. runs best on SUL 97

Just that little bit extra zip.

thought I was crazy at first (ex -optimax junkie)

Cheers

virgin

cheers guys, now i dont think i am nuts ! cheapest mod yet !, drop to 97 ron and save 6pence per litre, i knew there would be a benifit to running a scoob eventually

virgin

Not trying to get a big thread going or anything , but is anyone else running better on 97ron instead of 98 ?

Scoob99

iTrader: (1)

I knew it, I wasn't losing my marbles, I've run mine on SUL since I've had it and was wondering about optimax, now I know I won't mess around wiyh it
Cheers
Colin

akshay67

Marbles may be lost, but I can say one thing for sure - something I noticed last night - there are DEFINATELY more pops and bangs on my full decat with SUL as opposed to Optimax - that alone is enough to warrant SUL only from now on

harrymonk

Tried both 98 optimac and 97 sul dont feel and difference?

CEL

iTrader: (1)

I have to say i cant really tell the difference between optimax and SUL.

Still make a point of putting optimax in though

Terzo228

here we go again

chrisp

The funny thing is Optimax is Shells brand of SUL so when you say SUL you can also classify Optimax as SUL. So basically what you are saying is SUL is better than SUL .

Flat 4x4

I am 99% convinced that DODGIMAX caused or contributed to the meltdown of the engine of my UK Impreza 99MY.

But hey, lots of people still think its fanstastic, so what do I know ? I did run 25,000m in one year exclusively on SUL and Dodgimax and noted the MPG, performance and consistency. That was enough (back up by my short engine replacement on a brilliantly maintained and oiled car)to mean that Dodgimax never gets my money again

johnrb5

im the total oposite i have my99 rb5 i get better consumptiom on optimax and lots more popping from the exhaust

virgin

To reply to the comment Chrisp made, can you say optimax and SUL are effectively the same ? we are discussing the difference between opti at 98 ron and SUL at 97, there seems to be others like me , as in 97 is running better than 98,

Old stored fual at the stations could be a factor,however i have run at lot of optimax before going to SUL 97, and i sure there is a porformance difference, are there any others out there who think there car is running on 97ron better than 98ron ? or are the few of us on this thread ctotally nuts ? i am talking non chipped or boost clamped or re-mapped etc cars, just full de-cats front to back with induction kits

virgin

There must b someone else with the same experience ?

chrisp

All fuel degrades over time so why do you think optimax degrade quicker than other 97 . Surely if they all degrade then your 97 may have degraded as well. Did you read the link I posted o the previous page, answers the degrading question ?

There are plenty of people with knocklinks which light up on 97 RON and less on optimax. Think I'll still stick to optimax thanks.



[Edited by chrisp - 10/18/2003 3:34:47 PM]

chrisp

Actually thinking about it I would be more worried running 97 RON SUL as most people buying performance fuel seem to be buying optimax so the turn over of optimax must be higher as spend less time in the petrol station tanks.

You are running a full decat and induction kit. I hope its a pre 1999 UK car ?

Flat 4x4

We all learn by our own experiences, which is why we all make our own decisions about what we buy - cars, fuel whatever.

To back up a bit more my comments why I won't use Optimax, and to add more to the degrading issue, the 25,000m I did was in 8 months, which meant I was filling up frequently from a variety of garages (albeit 2 or 3 main Shell stations, plus BP, Esso and Texaco SUL.

I thought it was 'just me' at first but I'd noticed that with every few (4 or 5) Optimax tanks that the car didn't seem to be as responsive. I put it down to the weather conditions (temp and humidity) at first but it kept happening and as I was now noting the weather, it wasn't that.

I then deliberately used 6 tanks of SUL on the trot, then went back to 6 on Optimax. It felt roughly the same except for one tank on Optimax where it felt 'flat' like running on normal unleaded.
I then stuck mainly to SUL and occasional Optimax as when you are doing 800 miles every week you fill up when its convenient! I never had a flat SUL tank, but did have more 'still' rather than 'sparkling' Optimax.

So that was that, an honest appraisal over a fair few miles ?
Well almost. I was out of my regular area(s) and brimmed with Optimax. The very next day, I had been driving fairly 'spiritedly' and it started going 'clonk'

Pure coincidence ? Hey, well maybe it was - it happens to other standard UK cars sometimes. As this was the first car I had run on Optimax and I've owned 5 Subarus, my experience was that there is something not quite right in the consistency of Optimax that I have never felt in any cars I have run on SUL. My 10p's worth

nelly

I wish I could get optimax to give a serious trial but living on the Isle of wight we only get s.u.l. and reclently even had a drought on that, and had to make 50 mile round trip just to fill up. Still at least island b roads are fun to drive!!

dave_the_B

Ok, I'm not trying to out-do anyone here but....

My MY97 wagon,109k on the clock, center de-cat and STi back box, goes better on Sainsbury's standard UL(with a 4p off a litre voucher) than on SUL or Optimax :O

How strange...

Dave

virgin

Fair comment chrisp

virgin

Well , as in people with knocklinks, i am hoping that more experiences get put on this thread, people with knocklinks would have very very useful info to post, i still maintain it runs better on 97 ron as apposed to 98ron,
MY00 uk wagon turbo, You mentioned if it was a pre-99 chrisp ?

SlowBoy

iTrader: (1)

Induction kits can be very tough on the MAF sensor fitted to 99> cars.

virgin

just fitted the induction kit, seemed to of lost a bit of power ,but a smother power curve