Standard or Super unleaded in a M273 engine?

Discussion in 'Engine' started by ToeKnee, Dec 29, 2016.

  1. ToeKnee

    ToeKnee Active Member

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    In my past V8's I've always used super unleaded and altered the timing to give better power. The handbook of my current '06 SL500 states to use 95RON unleaded and I wondered whether anyone uses the super unleaded in their M273 powered cars and whether they felt it made a difference or not?
     
  2. rifiki

    rifiki Hardcore MB Enthusiast

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    Have V6 in my CL:K, no difference, just cost more.
     
  3. alabbasi

    alabbasi Hardcore MB Enthusiast

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    All Mercedes Benz in the last 20 years use variable valve timing. They will run just as well with unleaded or super as the computer will adjust timing appropriately. There will be an impact on performance due to lower octane levels, but not likely enough for anyone to notice unless you drive like a rally driver.
     
  4. rf065

    rf065 Hardcore MB Enthusiast

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    I think your getting a bit mixed up, variable valve timing is something completely different.

    Russ
     
  5. hotrodder

    hotrodder Hardcore MB Enthusiast

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    As said ignition timing and variable valve timing are very different things. Personally i usually use supermarket super unleaded as Sainsburys 97ron is typically cheaper than 'branded' 95ron around my way. Never bothered messing with the the variable resistance trimming knob to force things but in theory the ignition should still end up being retarded less (in some circumstances depending on the knock sensors etc) with higher octane fuel. Doubt it'd make a measurable difference to power or economy but (psychologically at least) even older stuff designed around 95ron often seems to run better on super, possibly because they were designed before anybody had conceived of adding ethanol to petrol in the name of environmentalism

    If the owners booklet just says to use 95ron minimum then it's probably not set up to take 'proper' advantage of super unleaded or it'd say something different and have caveats for if/when 98ron isn't used
     
  6. OP
    OP
    ToeKnee

    ToeKnee Active Member

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    Thanks for the replies. I might try a tank full of the super stuff if I get really low again and see if I can feel a difference.
     
  7. MWCLS

    MWCLS Hardcore MB Enthusiast

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    I only use shell V power as long as i can remember Fwiw maybe placebo effect. im currently running around in a lowly V6.3.0... boy does it shift ... slowly.
     
  8. Iceviolet

    Iceviolet Hardcore MB Enthusiast

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    I always put v power in my m273 powered cls, more for the additives in it to clean and lubricate the fuel system than the octane rating.
    I always think that a high quality engine deserves a high quality fuel and lubricant.
     
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