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Discussion Starter · #1 ·
I understand the the 225 should use super unleaded, does is state this in the manual and what affect does it have using standard unleaded. Will it cause damage or just reduce the performance.

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Uncle
 

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No damage at all.
The car is rated to use between 95 and 97 RON as stated in the megane booklet that comes with the car.
 
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Top gear did a good article on the different petrol brands a couple of months ago. They got a about 12bhp from a Golf GTi with bp ultimate than standard supermarket 95ron and cause its basically cleaner the engine is more efficient. I have been putting it in mine since reading this and the mpg has gone up by and average of 2-3mpg. It picks up better at lower revs too although I may just be imagining this to justify the extra money it costs :wink:
 

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PaulMcC said:
Top gear did a good article on the different petrol brands a couple of months ago. They got a about 12bhp from a Golf GTi with bp ultimate than standard supermarket 95ron and cause its basically cleaner the engine is more efficient. I have been putting it in mine since reading this and the mpg has gone up by and average of 2-3mpg. It picks up better at lower revs too although I may just be imagining this to justify the extra money it costs :wink:
not forgetting 40lbft extra torque :shock:

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Unleaded

All new cars supplied in the UK must be able to run on 95 octane unleaded. Some higher performance cars have two engine maps, and an octance sensor. These engines can produce more power from 97/98/99 whatever octane fuel, but can also re-tune for 95 when 98 isn't available.

The fuel is basically same stuff, the major difference is the presence of a detonation inhibitor in super duper unleaded, that allows engines to have a greater ignition advance.

However, when a non standard ignition map is loaded, the engine may require high octane all the time to prevent detonation.

In the sophisticated world of GTRs owners can load their own after market engine maps to retune their engines on the go. Plug in the laptop and away they go. I've also seen the same in highly tuned MX5s. I wonder if anyone will try and produce something similar for the 225? Anyone fancy a multi-tune engine? Say one map for commuting - standard maybe, another for weekends showboating and track days - max power, and the third for when someone of lesser ability needs to drive - seriously reduced revs and turbo boost - (I've a 16 year old who thinks I'm gonna let him loose in the 225 come next birthday).

Chris.
 

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Yeah the fuel is identical, in fact all unleaded fuel is based on the same product (I work for BP). The only difference is the additives that are blended with the fuel as it is pumped into the tanker. This is why at fuel depots you see loads of different brand trucks using all the same fuelling rigs.

There's no point putting higher octane fuel into a car that is tuned for 95 RON, complete waste of time. If you have the timing changed to match a higher RON fuel then you will see a benefit.

The only other reason to waste your money on the fuel is because of the extra detergents we stick in. Don't see any point really since a bottle of that additive you can buy will have the same effect if used now and again.
 

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my understanding was that with most modern engines the ECU can adjust the timing to match the fuel.

Although, as has been said, this takes some time ie a few tanks worth
 

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I suppose you could speed this up by running the tank dry with regular unleaded and then getting some super flowing followed by an ECU reset.
 

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I've always run the Megane on Optimax and my Clio 172 was the same.

Dunno if I'd notice anything different from it performance wise if I used 95ron fuel but I don't use much fuel so put about £15 worth of Optimax in a week, if that!! lol :lol:
 

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well after having the re map done running 97 ron from BP the car run fine with no pinking at all,
on the way home i filled up with £60 worth of OPTIMAX and god did she not like it, the car lost all power and jerked like a bitch for about 5 miles but after that all was hunky dory, got 31.9 MPG all the way home at 90 mph,

well friday night i had to pop out at 1am to get my ali from the station but i had no fuel in the car so i decided to just stick a £10 of normal 95 ron unleaded till i come accross a SHELL for more optimax, BIG MISTAKE, iv had to drive my car for around 60 miles with out putting my foot down or otherwise the poxy thing just jumped straight into LIMP MODE evry time.

phoned paul and he was bemused it was doing it as the map has bin on the car for 2 weeks now and iv not had any probs with all the time using the OPTIMAX in her, the only chnage iv made since going into LIMP MODE all the time was wen i stuck the £10 of 95 ron unleaded in.

iv give it some real stick with the OPTIMAX in her trying to get it into limp mode and nothing but a shot of 95 ron and its cripples the car,

so sunday afternoon while still running the shit 95 i come accross a TESCO which had the 99 RON unleaded in so with the fuel light on i stuck a full tank in at only 97.4p a gallon, so £49 later i set of,
pull out the garage WHACK straight into LIMP AGAIN. fuck me im getting sick of this, drove anothe 20 miles and she was still all over the shop, jerking pulling loosing power then, she settles, no more jerking nothing,
so i pull over turn the car off and restart her, pull away giving her some good revs and nail it in every gear and bugger me all is fine, not a bloody thing.

all the way home from my aunts in the evening GREAT no probs, but god can you feel the difference in the fuel, i even got 31MPG at 100 MPH all the way home with even dropping it down a peg from time to time to see if it went into LIMP MODE and nothing,
it feels more responsive better reving and even idle i think ?

from my own learning i will now never put 95 RON fuel in again, even 97 RON if i can help it but in emergances i will use it,

from now on i will only use this shit hot 99 RON from TESCOS with OPTIMAX in a close second,

iv never bin one to watch wat fuel i use but honestly how wrong was i.

sorry for the ramble.

andy.
 
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