Scoobydick

So Optimax is basically just like paying for octane booster and a decat over a long period of time in small installments Smart!

Gez

Hi guys,
Just spotted this post, i just put a post up regarding how rough my car is when the turbo cuts in. I also have had hesitation problems when cold so im starting to wonder whether or not it is the Optimax that im using. When i first picked up the car it had 95Ron so i immediatley put 97RON with 1/2 bottle of NF Octane boost to minimise det. The car was running very smooth and the acceleration was great. My second tank was Optimax with 1/2 bottle of NF and it was still ok. I filled it up again a few days ago and its been running rough so my guess is that maybe the Optimax had degraded and the fact that i mostly drive the car on weekends doesnt help. I think i will be switching to SUL until Shell confirm the RON rating of their petrol. Is it 98 RON or is it 95RON with additives taking it to 98 RON????????

TonyBurns

iTrader: (3)

Gez,
Optimax is a refined fuel, it wont be 95 ron with added octane booster, it will infact be refined at 98.6 ron as its cheaper to produce on a whole rather than adding afterwards (thus the price of optimax )
Fuel does go off but then again so does water etc, and even if you only use your car at weekends your bound to refill her more than once in a month so your fuel rating will still be higher, even with the added octane booster.
I wouldnt worry about it too much, ive never had any real performance loss running optimax (just a clogged wastegate pipe ) and the chances are that if you put SUL in there its going to degrade just a quickly as optimax anyway, leaving you worse off, both in pocket and in ron.

Tony

Mickle

nom you're a genius!

Hope you keep us informed as to the results

Chris L

Thanks Nom - made things a little clearer

Chris

WREXY

Don't forget that in that test in OZ, Optimax was tested agains 95 RON fuel and not 97 RON fuel.

andycrowther

glad i read this....been using optimax and it was very rough when cold......my01 wrx....worse than 95ron....filled up twice in last 2 days with sul and it's loads smoother....think i'll stick to the sul....sainsbury's sell it so i think that the little wife will have to go shopping there so i can get my petrol discount.....(she can use her own car...not touching mine!)

Devil's Refugee

John Banks has suggested that maybe Optimax has dislodged deposits already existing within the engine and this has somehow accounted for a rougher ride and loss of performance.

Seems to make sense also.

Devil's Refugee

Andy,

Avoid supermarket fuels.
Although they seem to be cheaper, they are in fact inferior to forecourt fuels. They apparently have less additives (correct me if I'm wrong here someone) present.

Usual story, get what you pay for.

Mickle

[Edited by Mickle - 7/5/2002 9:33:41 AM]

Chris D

I've been running my STi Type UK on Optimax from new and it has now covered about 2K miles.
I would be surprised if there were any deposits on a new engine since it only had 40 miles on it when I started using Optimax and yet, I am experiencing most of the problems above:

Rough engine, esp when cold - lots of hesitation
Uneven power delivery - it seems to come in fits and starts particularly when exiting 2nd gear bends on full throttle.
Reluctant to start.
Thrashy at high revs.

I had assumed that the above problems were either a 'charcteristic' of this model due the the emissions equipment (ie 3 cats) or would improve as the miles increased.... but perhaps some of this is due to Optimax?

Still hoping that the ECU amd exhaust change if the PPP is ever released may improve the situation.

Anyone else had similar findings with new STi's?

Chris

Devil's Refugee

I've had a couple of e-mails off-line with John re this subject but he hasn't tested the fuel so it was a mere suggestion and not a point in fact. Just to let everyone know.

Davej_Smith

I collected my STi UK at the weekend and had to fill up with NUL as that was the nearest garage and the fuel light was on!

I have since done just over 200 miles and have experienced NO rough running when cold, hesitation, although with such low mileage I am still taking it fairly easy.

Think I will use SUL untill this is resolved.

TonyBurns

iTrader: (3)

Chris, your car isnt going to be at its quickest yet and as for the 2nd gear out of the corner accelleration.... if you sit on 2nd gear for too long (think the new STi will have this feature too) then the emissions settings cut in that means you have to blip the throttle to get the power going again, it may seem like hesitation but is infact built into the ECU.
I'd wait till the PPP is out, get rid of 2 cats and let the car breath a little just dont expect a new car to be too responsive until its got 5k+ miles under its belt

Tony

Chris D

Thanks for the info Tony. I agree, it will probably be more powerful once it has covered a few thousand more miles.

STi UK ownership is a long drawn out process:
First the 7 month wait to get it.
Next waiting for the 1,000 mile service before going over 4K RPM.
Now waiting for 5K miles for some decent performance.
Waiting for the PPP - who knows how long!!

I just hope it will be worth it, cos at the moment compared to my previous standard MY98 with a Scoobysport BB it doesn't feel that quick and certainly doesn't sound as good.

Gez

After chatting to Dave Medcalfe of Lavender Hill garage he suggested that the advantages of Optimax will only be fealt after quite a few tanks ie more than 2 or 3. In most scoobs the engine will run rough due to the dislodging of deposits in the engine so if you switch to SUL the engine will smooth out again.
What i want to know is if Optimax does dislodge deposits, what will it do to a new engine?? Would it cause more harm than good? I think fro reading all the posts a long term test should be carried out either by shell or an independant company.

Devil's Refugee

Trouble is, I doubt Shell would be able to conduct an impartial test
And without promoting an X-Files conspiracy I'm sure any other independant tests by petro-chemical experts would be doctored for a bung, hehehe

I'm putting my money on Nom coming back with something.

nom

You may have to wait some time for nom to come back with something - slow moving stuff, this

John - I ran 98RON Esso (passing through Belgium) & the Optimax (back in UK from what seemed to be a busy station) same day & logged the whole lot. Same weather & pretty much everything (reset ECU at each tank). Zero - and I mean absolute zero - knock correction with the Esso 98, the usual -2 and up to -4 on Optimax (98.6 RON?!?). That's an MY00 with Tek2.

Mickle

Just filled up with SUL after 2 tanks of optipants. My hesitation accelerating when cold is subsiding. Yesterday it was still noticable, today it's barely there.

Good old SUL

davek

Ive had my my00 for 3 months now and since day 1 have used optimax.However, after worsening sluggish cold starts and the feel of overboost when flooring in 5th i tried a tankfull of esso super plus last week.The difference as been amazing its like a different car. Smooth when cold and all the way through acceleration, definitely the best feel since i picked it up.Im nearly out of this tankfull but will stick with it for a few fill ups then maybe try 1 optimax to make note but im sure this is the way for me now.

scoobypig

My ppp 02 hates the stuff.
OK occasional but if all the time,feels like something wrong with it.
Could do an ecu reset with it but then will it dislike normal SUL?
I reckon the hype will fade...