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Ta, good to see another set of ethusiasts opinions on Optimax. I'd like to see a good independant report before I start panicking about whether or not it's dissolving my engine though!

Regarding the RON decay issue, if true, this would be a problem for me as I only refil about once a month. I will try putting in a "fresh" tenners worth every week and see if theres any difference.
 

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Discussion Starter · #3 ·
I had a problem with my car starting to run a bit rough & the engine was cutting out for no apparant reason.
You do start to think of all sorts of think, fuel tank surge was one the other being a possible problem with optimax.
I then discovered a big hole in my k'&'n induction pipe caused by touching the exhaust manifold & melting
.....got some lagging on it & hey presto back to normal
so whilst it pays to follow debates closely, don't become a "hypocondriac" if you know what I mean

shunty
 

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Interesting thread.

Indeed, who knows what Optimax detergents will do on an engine in the long run - only time will tell. New fuels have been withdrawn in the past, I recollect.

But as Shell standard UnLeaded fuel boasts a good cleaning properties (and i am sure Shell didn't compare Optimax to their std unleaded when they showed us lpictures of dirty valves against Clean Optimax valves!!), then I would say use Shell std unleaded - and save your money, unless you specifically want the extra performance Optimax gives.

Not forgetting the claim on the Scooby net thread which states Optimax Octane rating degrades by a factor of 2 over 5 days.
 

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Discussion Starter · #5 ·
hey Paul, that's a bit worrying if it's true about the ron degrading by 2, escpecially if you are running higher boost & custom map, with different fuelling etc.....could throw a spanner in the works.
John Felstead from scoobynet raised a good point stating how could you set up your ecu with custom map with regards to fuelling, if you are getting possible degredation of ron when you are testing your set-up


shunty
 

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Shunty,
I agree, although not too many folks will be running cars with custom mapped ECU's relative to fuel, like myself.

Not sure that it is a good idea to go to such levels though, unless one is willing to constantly remap ECU depending on fuel used, etc.
Unless a fuel station pump is branded with a special type of fuel (e.g. Optimax) it could contain petrol from any given supplier, within the permitted Octane level tolerence!

Mixing different fuels will definately affect Octane rating, and performance, if we are looking at the 'nth degree' of performance. Formula 1 teams constantly monitor & analyse fuel for performance and regulatory reasons. Mixing two different types of fuel, both of which fall within permitted spec, can result in a fuel outside of regulations, hence result in a penalty, etc.

Suprising though that fuel octane rating (Optimax at any rate) allegidly degrades so quickly.
 

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Discussion Starter · #7 ·
Paul D, I don't personally run custom map, although I would have gone that route if I'd have known how to do it earlier on when I started modding my car.
Personally I know my car is just a scooby not a Ferrari like some of the guys on there do
so fuel degradation is not vastly importantly to me as I am only running about 17psi.

ps - my saab is a beutiful motor, very, very impressed with it. The wife loves it better than the scoob
, more comfortable, less noisy etc....what does she know, she's a girl

shunty
 
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