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  1. #1
    Tadpole
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    Default Premium Petrols in 205GTi

    Hi everyone.

    I'm sure this has been discussed earlier, but there are now so many different options when it comes to fuel, with loads of different octane ratings, that I'm curious to know whether

    a) the computer in an S3 205GTi can make use of higher octane fuels

    b) whether anybody can actually notice any improvements in performance/economy

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    Or would you need to chip the motor for real gains, since petrol standards in the early nineties probably operated at a lower RON than today.

    tt

  2. #2
    Member semerton's Avatar
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    I use 98RON because the marketing men say that it cleans your engine... Not sure how true this is, but it makes me feel nice

    That terrible 'drive' show on channel ten had a brief bit on either optimax or bp ultimate where they showed how crap from the engine was being cleaned off after a few thousand kms. A bald guy pointing at a dirty engine and then a clean engine is enough to get me to spend an extra few dollars each week.

    Not sure about any performance or economy benefits.

  3. #3
    Tadpole
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    Second to that thought about the bald man; if somebody who claims to know what they're talking about mechanically tells me something, I'll smile and nod my head.

    Reminds me of the Seinfeld episode where George is complaining about mechanics ripping him off, and says a mechanic could well say the car needed a new 'Johnson Rod', and he'd have no option but to agree , even though there probably is no such thing.

    But anyway, the question really is whether a car of that age can tell there is a higher RON fuel in it or not?

  4. #4
    Fellow Frogger! SydGTi6's Avatar
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    Higher Octane fuels have longer molecular chains and therefore are more slow burning. The reason they are suggested in European vehicles is that they generally have 'high-compression' engines. With a fast burning (lower octane) fuel, you risk premature 'detonation' on the compression stroke, where your combustion chamber fires before the piston in that cylinder reaches 'top dead centre'. Of course -this damages the engine or may cause you to burn out a valve, etc.

    Higher octane fuels will generally provide a smoother burn, even in cars without computer ignition management. From memory the 205 GTi engine runs a fairly high compression ratio - so would be right at home with a high octane fuel.
    Last edited by SydGTi6; 2nd March 2006 at 03:00 PM.
    Black Peugeot 306 GTi6, Sydney Australia
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  5. #5
    Member alexi's Avatar
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    I think the minimum suggested RON in the manual is 95, from memory standard shell premium is 96 and shell optimax is 98. I think the optimax is supposed to be a very clean fuel, i.e. if used over time it will not contribute many un-desired deposits in the cylinders. I think optimax is even supposed to actively clean the engine, I'm not sure about this but again the media hype makes me believe this is true.

    I have used optimax in my car for a while now and it seems to be the best fuel for 205 GTI's, this is only my humble oppinion though.
    Alexi 1988 205 GTI (Graphite Grey, series 1)

  6. #6
    Member semerton's Avatar
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    Quote Originally Posted by Tubbsy
    Reminds me of the Seinfeld episode where George is complaining about mechanics ripping him off, and says a mechanic could well say the car needed a new 'Johnson Rod', and he'd have no option but to agree , even though there probably is no such thing.
    Are you sure the 'Johnson Rod' isn't real? Could have sworn I had two of them replaced in my last service

    I'm pretty sure the 205GTi will run fine on 91RON, as it was detuned for our market...

    I know alot of people that are certain their cars prefer a particular brand of fuel, but I can't seem to tell the difference.


    This is BPs story about cleaning your engine...
    BP Ultimate also contains corrosion inhibitors to protect the fuel system and has less than a third the sulphur content of regular unleaded petrol which means less harmful polluting emissions! Constant use of BP Ultimate will keep the engine clean and free of deposit build up on engine valves and injectors that inhibit performance. Naturally, a cleaner engine means less wear and tear - and that can really pay off in the long term

  7. #7
    Tadpole
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    So does that mean the 205 could be tuned to take better advantage of premium? It's pretty widely available these days.

  8. #8
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    Default fuel

    My 87 205 gti (series 1) works best on unleaded. Premium unleaded results in no difference in performance but a slightly lighter wallet after the refill.

    My wife's 92 205SI with a 1.6 litre enmgine does work better ( performance) with premium unleaded.

    Fifth Gear ( car show on fox) tested euro regular unleaded, BP ultimate and Shell Optimax in three cars in its show this week. In the Renault Clio they tested ( not sure whether sports version or regular plodder) there was no difference between the fuels.

    However the Subaru WRX ( if my memory is correct) recorded an output some 10 - 12 kw more on Optimax than regular unleaded with Ultimate in between the two.

  9. #9
    1000+ Posts PeterT's Avatar
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    Even though the S3 GTi has a Motronic 1.3 like the Mi16, it does not have a knock sensor, and therefore cannot make use of higher octane fuels. With it's 9.2:1 CR, it probably runs best on 95.

    The worst petrol in terms of deposits is 91. Any car that has run on 91 all it's life will need the injectors professionally cleaned at 100 000Km. The difference between inlet manifolds that have run on 91 or 98 is amazing. The later are squeaky clean, the former black with carbon deposits.

    '92 205 Mi16
    '90 Mi16x4

  10. #10
    Fellow Frogger! bazgti's Avatar
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    i run 98 but have used 95 but i reckon it drinks 95 noticibly quicker.
    also ive never had to clean my injection system using 98 and being a old hippy,if 98 runs cleaner and better for the ozone etc,ill pay that extra few cents.
    there is now 100 octane out there for all those with high compression motors who want to take advantage of the extra oooomph.
    the rst of us can only hope-BAZZ
    BAZGTI
    87' 205 gti anthacite grey
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    momo steering wheel.

  11. #11
    1000+ Posts Dave's Avatar
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    Quote Originally Posted by bazgti
    i run 98 but have used 95 but i reckon it drinks 95 noticibly quicker.
    98 fuel has a higher density.

    Dave


  12. #12
    Cub
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    Hi guys,

    Given the fact that 95 RON is recommended and there might be variances in Octane count at the servo, I just think its safer to run 98 Optimax...as for the cleaning agents, I also listen to the bald man's suggestions!

    Thats my

    Cheers,

    Stan
    CUB

  13. #13
    Veni Vidi Posti 68 404's Avatar
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    Just remember in Sydney there is just two oil refineries:

    Caltex and Shell.

    Hmm, I wonder where the other brands get their petrol...?

    Dave
    2008 Renault Laguna 2.0 dCi break
    ​1997 BMW K1200RS

    IR655
    (George Bush Snr): "I'll never apologize for the United States of America. Ever, I don't care what the facts are."


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