Hi folks just a quick question for you all am i gonna notice any difference at all running with optiamx on a standard turbo impreza compared to the usual unleaded it normally gets just wondering if there is any justification for the extra 5p a lit ?




Pongo555

 

you should feel quite an increase...

TBH i dont run on anything less

 

You should always use SUL/Ultimate or Optimax. Best performance and protection for your engine.

 

You can use 95RON UL in a standard UK car, but you won't be getting the best out of it. Your ECU should be capable of retarding the ignition enough to protect your engine against knock, but why buy a performance car and use crap fuel...?

 

I ran my 98 UK Turbo on Safeway's Finest 95RON for 18 months when I first had it without any issues. BUT, I switched to optimax when I started 'tinkering' with it and haven't used anything else since......

 

Thanks for the help guys and the car is on its LAST tank of ****e fuel then lol optimax from now on lets see how it goes lol cheers again guys .



Pongo555

 

You might want to try resetting the ECU as well, to give it a helping hand at advancing the ignition. I think you need to use a couple of tanks of Optimax first though...

 

Shouldn't need to reset a 98 MY ECU - I'm told (Graham at TSL) that it (and the 97) are self-resetting (I wanted it doing and he said 'no' and didn't charge me - )

Mark

 

- My import hates running on optimax (tried three tanks full!) - It felt sluggish and underpowered - I went back to Super Unleaded - it flies!
Incidentally when I approached Shell about Optimax's octane rating(2002) I was told that it was 98 RON, yet no one could give me any paperwork to back this up!

To answer your question : it burns better than unleaded so in theory it will either give you better performance or better fuel economy - I did say in theory though !
As for ECU resets I am told, if you leave the battery off, for an hour or so, it should do the job.
Again there seems to be a view that ECU's adjust one way better than the other (with imports anyway).UK ECU's I’m not so sure about!

 

I have owned my scoob for 18 months, and never used optimax, only esso sul, last weekend nearly emty tank and went into a shell ststion and filled up with optimax, so far, no difference at all.

Will prob give it another 2 tankfulls but i have my doubts.

 

It is strange how some cars prefer Optimax, and others prefer SUL. Personally, mine prefers BP Ultimate. Weird eh...?

Markwild, you're right about certain ECUs self-learning, but it doesn't hurt to reset, and could even uncover pending problems you didn't know were there (MAF for instance)...

 

I used 95 ron for the first few months when I got my MY99 at the end of 2002 , then changed to Optimax and noticed that it did run a little smoother but that was about all , I changed back to 95 ron a few weeks ago (just to see if I would see a big difference ) , and I cant really say there's that much in it at all

Dave

 

I wouldn't use 95 if I were you - the minimum they are meant to run on is 98 (yes, including UKs - just look at one of the Euro cars which are identical in every way, except don't have the ridiculous PC ****e we have to put up with over here).
If you have any instrumentation that shows you what's going on when you put 95 in, you'd barely feather the throttle. I had to use some a couple of years ago & could barely touch boost without nasty lights flickering about.
Watch-it with that stuff!

 

I think Nom's hit on a valid point there. A question to all the people who've said...

"I've tried both and can't notice any difference..."

Do any of you have a Knocklink...?

 

Petenaud,

You mentioned you filled up your car with Optimax, on a empty tank...how much did the full tank cost? Also how many miles did you get out of that?

Sam

 

I certainly noticed a big difference with my Knocklink activity switching from Optimax to BP Ultimate. I'm too scared to see what NUL would be like

Certainly on my MY99 Optimax appears to reduce the risk from detonation.

Stefan

 

Petenaud,

You mentioned you filled up your car with Optimax, on a empty tank...how much did the full tank cost? Also how many miles did you get out of that?

Sam

 

Back to Optimax for me then !

 

Without a Knocklink it's difficult to say what effect NUL has on any car. I would be surprised if it was anything but bad news, but it depends on how it's being driven.

If it was motorway cruising at 65mph or short-shifting around 3000 rpm then I doubt you'd be in much danger.

Again, it would also depend on the level of modifications on your car. I have the std AE801 ECU, but have a full de-cat (TSL DP, TSL centre + STI back box). Everything (other than suspension is std MY99 RB5), but running BP Ultimate had my knocklink looking like a Xmas tree at almost every gear change above 4,500 - 5,000 rpm.

Stefan

Stefan

 

Bizarre. It was the other way round for mine, Optimax was "sparkly" (never Christmas tree though), and Ultimate quietened it substantially. However, Ultimate + Millers allowed the boost to go up a further 2psi (UK MY00, H&S SON DP, OEM centre, H&S silencer, K&N panel filter, Dawes ~18psi). I wonder if the added richness/retarded ignition of the AE802 makes the difference...?

 

I read somwhere that Optimax was tested straight from the pump and was showing 97.2 RON and after 3 days in the tank it had dropped down to 95 RON.
Now ask yourself how long does it sit in the petrol station tank before you buy it and then how long is it in your car for (Subaru's not very long).

By law Optimax only has to be 95 RON when its sold it may well leave the refinery as 98 but it only has to be upto 95 Ron @ point of sale.
It makes me wonder as my MY01 ran good on some tanks of Optimax and bad on others.

Zippy

 

Hmm....Intresting...!!

Can this be true...I mean i have had good and Bad days of Optimax!


May consider switching to Super Unleaded.....

 

Is there any similar research into BP Ultimate...?

 

In the 4,000-5,000 rpm range (the sparkly bit on my car)...
Taking Optimax (from a low turnover garage - makes a big difference with Opti!) I have to remove 2 degrees to prevent occassional det with Esso SUL, but have found Esso to be very reliable (ie identical from tank to tank), and 5 degrees with 'Ultimately Pants' to stop det. What's more, the BP stuff appears extremely variable - sometimes it'll take more, usually it won't. A bit of a nightmare if you ask me... I think I'd prefer to put in NUL & wop in loads of additives than use that stuff!

 

Have been recomended to use a can of octane boost on every tank full. It lasts longer and doesn’t deteriorate as fast as optimax ron does.

Intresting.....

 

'Home-added' booster will deteriorate, though
The most 'reliable' way of knowing the RON you are getting is sticking to boggo SUL. That should barely deteriorate at all. But that only helps if you can map your car to suit it

If it is of any interest to anyone, I have found (by measuring engine 'noise level' rather than guessing ) that Optimax does deteriorate over time - I have taken a month to get through a tank in the past as I don't use the car every day - but it only effectively lowers itself to a RON level I'd say equivalent to slightly above Esso, the best of the SULs if you ask me; i.e., it doesn't drop below ~97 RON.

Which, in my books, even with its shortcomings, makes it the best 'off the shelf' fuel, if a little variable

 

correct me if I'm wrong but I believe SUL has to be 97RON to achieve the BS. Optimax however is not sold as a Super Unleaded and therefore does not have to comply with the BS. Optimax is a 95RON fuel made up to 98.6 RON using addatives.

 

So really you're probably best of using normal unleaded 95 ron and using an octane booster to raise it to 98+ ???

How much is octane booster and how much do you have to use?

Is it cheaper to use normal 95 leaded + octane booster than Optimax?...

Matt.

 

I wouldn't say that. Other know a lot more than I. That was just my understanding

 

I think the best way of testing is to simply fit a knocklink and try different fuels and see how much it lights up.

Personally I don't trust the stuff that comes out of the pumps, hell they could put what they like in them, mix them up, who knows?...

At the moment I use Optimax from a local garage and the car seems fine - think I'm gonna by myself a Knocklink!