Noticed over a while that a some of you choose to use 98RON petrol (Shell Optimax for example) - especially those with remaps.

Is there any advantage to gain from using this in a standard car? Just wondering as its relatively cheap at the mo round here (83p / litre) and my local garage is a Shell garage.

Cheers,

DaveJ

Haven't got my vrs yet...picking it up tomorrow, however, I've been using optimax and BP Ultimate in my 1.3 Nissan Micra for a good while now and it makes a difference. The car is a lot smoother to drive and seems more lively. Had to put std fuel in over the last week or so as the pumps at the local station were out of order, and the car now feels sluggish.

If it improves my present car, I would imagine you would feel a difference in yours...suffice to say I will be filling my vrs up tomorrow with either optimax or BP Ultimate...

Ventmore

I found It made a big diffence 0 - 2000 rpm before the turbo spools. felt very flat otherwise compared with normal unleaded (95RON).

compared with SUL (97 Ron) is far more subjective and has been the subject of debate many times before.

edited to add, if you dont feel any difference after one tank. try a second tank full. The benifits can sometimes only be felt after a few tanks.

I found It made a big diffence 0 - 2000 rpm before the turbo spools. felt very flat otherwise compared with normal unleaded (95RON).

Do you mean that the car felt more flat with the optimax or the normal unleaded?

Ventmore

sorry, flat with normal. It will feel better with optimax esp after a few tanks.

if you dont feel any difference after one tank. try a second tank full. The benifits can sometimes only be felt after a few tanks.

That was my next question! Did wonder if the car would take a while to get used to it. Need to fill up tomorrow, so think ill give it a go.

Ventmore, good luck tomorrow picking the car up. Make sure you give it a quick once over to check all is perfect. Its the best time to get things sorted - before you accept it.

@fastVeRSion

Cheers mate...can't wait to get it. I will certainly give it a thorough check over though before I drive it away.

Ventmore

I find BP Ultimate is generally better quality than Optimax (albeit more expensive). Optimax, IIRC, is normal 95 RON fuel with an octave booster, rather than proper SUL.

I've found Optimax to be inconsistent, even buying it from the same forecourt. One week it could be great (better than Ultimate), next week it feels like I've filled it with Asda's "Extra Special" diesel'n'grit.

... fuel with an octave booster,

Makes your engine sing?

Got both a BP and Shell local, so i'll have the chance to try them both over the next few weeks. If i can feel the difference, then i suppose i'll stick with the one i find feels better. Have tried optimax on my bike in the past, but didn't really get on with it. The bike felt like it was running on treacle, does that make sense? It just lost its zing somehow..

Optimax = Dodgymax ! Theres been lots of discussion on various forums about optimax being rather inconsistant (had experience of 1 tank like rocket fuel, another and milk floats pass you!!) and being the cause of engine failures (scooby net?). It would appear that it has a short shelf life and/or has very specific requirements for storage. As others have said Ultimate is a completely different approach and imho is the better option, either diesel or petrol. (Both mine run on ultimate) Get a smoother running and more econimcal engine consistantly.

As others have said Ultimate is a completely different approach and imho is the better option, either diesel or petrol. (Both mine run on ultimate) Get a smoother running and more econimcal engine consistantly.

Ran with Optimax in the Scooby religiously and saw an increase in performance and fuel economy. BP Ultimate made it run very roughly (yes I did try 3 or 4 tankfuls ) and according to the majority on Scoobynet causes large amounts of knock in the Scooby engine. Not had a chance to properly try the BP Ultimate diesel or Shell Diesel Extra properly on the Fabia yet....

Chris

The age old Optimax debate.....

.....IIRC Optimax is really unleaded which then has an additive put in the storage tanks.

I've found it to give better, smoother response.

BP Ulitmate is more consistant but doesn't "feel" as good as Opitmax...also a lot more expensive where I live.

Fabrezza put Optimax down to causing his Scooby to go pop.

The only claim that I see Shell makes is it cleans your injectors - i.e. it has a Redex type cleaner additive. As with any high detergent product inc oils, use on older engines which have not used them previously can cause major problems.

IIRC Shell has tried this product two or three times over the last several years, and one incarnation was withdrawn following a lot of lawsuits regarding engine damage.

BP seem to be offerring a properly enhanced product with performance claims. But there doesn't seem to be anywhere as many BP stations as there once were.

Yes and no. No for the dodgy tanks, yes for the good tanks.

I'll use as and when, but the when is only when I can run 3 or 4 tanks back to back, otherwise I'll skip. Might drop a bottol of stp booster in on 95 if I'm feeling kind.

However there is a difference if you get a map/off the shelf whatever for 98 then run 95...it will possibly hurt your car and wallet. Hence I only run my 98 program when I know it's on 98, then if I can't find a shell, I'll change to 95 and still have the fun

The difference between the two is good enough to be felt in the ass dyno *assuming it's good stuff* That said I don't think I've ever had a really bad "this feels dire" moment.

The only claim that I see Shell makes is it cleans your injectors - i.e. it has a Redex type cleaner additive. As with any high detergent product inc oils, use on older engines which have not used them previously can cause major problems.

They also claimed that it increased engine response.

IIRC the higher the RON value the less likely the fuel is to detonate (Explode before the spark plug ignites the fuel/air mixture)

The only time I would personally use Optimax or the BP variant would be in a high compression car eg. A Turbo.

It would be pointless to run it in a non turbo car unless it was running a very high compression setup.

That is IMHO but that's the way I understood it, BTW I have also heard Optimax RON value is made up by using normal petrol and adding additives to it so you might get a varied RON rating depending on how it is stored and mixed together as I think storage plays a big part in petrol RON value. Someone mentioned optimax has a few days shelf life before the RON value drops so fill up straight after the tanker has been.

Shell claims increased "responsiveness" though cleaner injectors - not an increased RON rating (only BP claims increased RON)

From the Shell website

Shell Optimax is specially designed to clean your engine as you drive. It helps remove deposits on inlet valves and ensure fuel injector nozzles are kept in tip-top condition. This is one of the reasons Shell Optimax can begin to improve your vehicle

Shell claims increased "responsiveness" though cleaner injectors - not an increased RON rating (only BP claims increased RON)

Who said that ? Besides Joe Public wouldn't know what RON ment anyway !

The only evidence I have seen of an increased RON rating is the labelling on the pump, but there again you could label the pump up with the Words JAM & CUSTARD but don't mean you are putting this in your tank.

If it does have a higher rating, Joe average probably wouldn't be able to tell in the engine response anyway, it is the feel good factor I believe and a way to make the petrol companies money for old rope.

Thw whole Optimax thing is very perplexing.

All I know is that it gives a chrisper and smoother response even though I have no data to back it up.

It's not a perceptional thing either as I know how my RS peforms. I tried Ultimate and while I found it the engine ran as smooth as Optimax, it did not feel more response and gave less mpg.

I guess it's like a person's choice of tuner.....you use the one your happy with and pay whatever it costs.

p.s Opitmax is rated at 98RON and Ultimate at 97.

Some people on this thread have referred to Optimax as having a RON (octane rating) of 98. It is standard premium unleaded (95) to the BS requirement. BP Ultimate is 97.

Only some cars have a ECU which self adapts to RON level.

Some people on this thread have referred to Optimax as having a RON (octane rating) of 98. It is standard premium unleaded (95) to the BS requirement. BP Ultimate is 97.

Only some cars have a ECU which self adapts to RON level.

I think you'll find it is 98 RON (Research Octane Number)

http://www.millersoils.net/pdf_downloads/Millers_octane.pdf

As tested by Millers.

It's not sold as 98 ron but the Octane is greater than Normal unleaded isn't it.

BTW do you require a Knock Sensor to adapt for different fuel types ?

Something posted by RevoKev:

I've monitored my own 1.8T with both Optimax and Ultimate, and yes you will have no problems with running the 98ron setting with Ultimate. I've also noticed that Optimax can 'go off' although 98% of the time (if you fill up at a larger garage where it's regularly changed) it is more efficient than Ultimate.

Hmmm....don't you find it strange that Shell doesn't claim its 98 RON after all that would allow them to charge a premium? - it would effectively be super-unleaded and a big selling point...

No, I personally, don't accept "the evidence". :holmes: Looks like more marketing hype to me.....

AFAIK self adapting ECU's require knock sensors and programs that run the timing constantly at advance angles producing some knock. (don't know if thats advisable on a high performance or turbocharged engine! :hbomb: ) Most modern ECU's are programmable (via VAGCOM or other means) for fuel RON. Something that Joe Public can't touch, and is factory set according to market country.

Anyway - back to that chap that ran his car on seawater back in th 70's...... :read:

From Shell's web site (admittedly hidden away in the "classic cars" section):

"Today, Lead Replacement Petrol has a minimum octane of 97 RON, Unleaded of 95 RON, Super of 97 RON and in August 2001 Shell introduced Shell Optimax, which with an octane rating of 98 RON is the UK's highest octane petrol."

And they do charge a premium for it!

OK I accept that...

Strange they don't push that on the Optimax pages. :confused:

But then its strange that they overquote their oil reserves....

Locally, its about 6p dearer than supermarket petrol.

AFAIK self adapting ECU's require knock sensors and programs that run the timing constantly at advance angles producing some knock. (don't know if thats advisable on a high performance or turbocharged engine! :hbomb: )

The Renault Clio 172 and all models afterwards have knock sensors, they basically advance the timing until a knock is detected then they retard back slighty to get the best performance for the variable (Petrol/Air temp etc) presented to the car IIRC.

So why is this not advisable ? If you have a sport engine surely you want the best out of it ?