I have always slated Optimax after trying it a few times. When the Gems went in I had Esso Super in. Steve was mapping and commented that the car kept getting det. We stopped at an Optimax and filled up. (Only little amout of Esso left in tank) As I drove down the slip road Steve mentioned that the fuel was already better and the det had gone. As a result I got more advance and torque. I am happy. Optimax works. Can't argue with Steve, the laptop and Det Cans.

Knock Link will be going in soon just to be safe.

 

Optimax is 98.8 RON, normal super unleaded is 97 RON. RON is a measurement of resistance to knock, so it's no great surprise

 

i use optimax. always have, always will

virtually no activity whatsoever on the knocklink

 

so why do I get a big fat flat spot in the mid-range every time I run Optimax? Car runs like a dream on Esso S\UL.

 

Have run MY00 Classic Turbo on both, now just run on Optimax, gives more power and a quicker, cleaner responce.

Matt

 

Viper - What Model Year is your car? I have a MY96 and ran it in standard ECU on Esso Super. It never missed a beat and hated Optimax.

Now with the Gems it clearly showed that Optimax was running it much better.

Perhaps early MY cars have more problems with Optimax and the ECU.

 

mmmm

I am not sure I think its as simple as Optimax is best... Petrol comes from the gulf and from the North Sea. Petrol is an organic compound therefore both sources are likely to be different. When I drove diesels I understood gulf fuel was "better". Chance dictates where a given tanker load comes from.

The stuff you buy at the pumps is labelled by octane rating... certainly my right foot prefers super varieties. Optimax is a super unleaded formulation. The RON figure should indicate a fuels suitability.

All manufacturers use fuel additives - Optimax claims in some way to be special.

How can you be sure that the label on the pump matches the fuel delivered through the nozel? what is there to stop a garage selling ordinary as super?

I think I am trying to say - I reckon it may be all pot luck - I certainly get some tanks that feel quicker than others and there doesnt seem to be much consistency by brand, but I always try to buy super.

finally - does anyone remember the formula shell fuel and the failing vauxhall engine allegations back in the 80's?

 

I would always use optimax too if my local shell didn't keep running out of it...

 

Sith - MY00. Recently had a service so filled up with Optimax b4 and asked them to reset the ECU, same problem! As the advert says, Optimax - feel the difference!

On the subject of fuel being what it says on the pump I did notice 2 people in white overalls taking fuel samples from my local Shell the other day, maybe a visit from the 'secret police'

 

BTW 'GEMS'???
(pardon my ignorance)

 

You know that it is not just unleaded because the trading standards would take them to the cleaners.

 

Bobby G no they wouldn't as they only ever registered optimax as a 'normal unleaded' & not super unleaded.

Optimax wont go near even my lawn mower!

RON rating is useless, compare the MON rating if you want a meaningfull figure, & look how much lower it is with Optimax.

Ok this is the nerdy bit from another forum:

There's enough reasons for me not to use Optimax

 

My car hates Optimax as well. I get the mid-range flat spot. Car is a P1. I'd love to rave about it because the idea is good, it just doesn't suit me

Maybe an ECU reset would help?

 

Viper - Gems is a Motorsport ECU. Fully 3D mappable. Very impresive piece of kit. Gems ECU's are used by Prodrive for the WRC cars. If it's good enough for them....

You've blown my theory out of the water aswell of being early cars. Oh well.


[Edited by Sith - 12/30/2003 11:03:14 AM]

 

I get the mid-range flat spot too. I switched to BP super (not branded as ultimate) and the flat-spot disappeared and the acceleration felt better. I noticed with BP that the exhaust was getting blacker than usual, so I switched back to optimax, and the flat spot gradually returned. Maybe mixing BP and Optimax would help? (WRX03 PPP)

 

I have run my STi5 on both Optimax and Esso S/UL and, frankly, the only difference is the price (Optimax is cheaper so I tend to use that) - the power boost from this cold weather costs **** all, now there's a bargain !!

 

I notice that when i run on BP ultimate my eninge is smoother and quieter ?

Dont really feel any difference in performance over optimax
My03

 

Ive used the BP stuff and prefer that!! (sorry for the technical jargon) :P

 

MattM

Yes! Used it in the then rally car and it worked a treat ... but it was a Hillman/Chrysler/Talbot Avenger not a Vauxhall.

It was better fuel as it had flame front enhancers ( potassium salts IIRC ) in the additives, which created a faster more even and thorough burn so releasing more power. Made most normal cars crisper and responsive. Basically the additive did the opposite of the lead in the fuel which was there to prevent knock/det/pinking.... so I guess you could say it was nearer unleaded petrol, in effect.

Unfortunately the then new engine design came out of Vaulhall, typically in the Astra, and that ran near what we would call Det. So increasing the fuel burn speed ( and reducing the effect of the tetra ethyl lead )led to det / pinking and engine damage.

Allegedly.

 

Always use optimax in my 00 PPP, pulls clean, quite, and goes like ****! what more can you ask of petrol?
dave

 

Misty

Lower price?

Less pollution ( yeah, they ARE working on it )!

Otherwise Optimax is fine for me!

 

if you try ultimate you have to put in two tank full of the stuff.
and it works.as above it is smoother quiter without flat spots.its been said so many times.it got to be good for your engine folks.

 

The Vauxhall engine failures were on what was generally known as 'Australian engines ' to us.

If so say no more, wouldn't matter what fuel you put in em........

David API Engines