super unleaded ???

gizze

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Cars have knock sensors in them, some are set up for 98 ron, some 95 ron.

If your car is set up for 98 ron adding 95 ron is stupid, you will lose refinement, mpg and power.

If your car is not set up for 98 ron adding it is pointless.

Strangely many Mercs are not set up for 98 ron. Most of the turbo cars are, as well as all AMGs. Many of the NA cars are not.


My 335i lost 30hp on 95 ron, plus it was down roughly 10% MPG too, so a 5% saving at the pump is a false economy.

Mercedes UK doesn't know if the E350 is set up for 98 ron or not, brilliant!

The US manual says 93 octane (like our 98 ron) must be used to achieve the advertised power and economy, so I reckon it is actually set up for 98 ron. I would presume the 500 is too?
 

gizze

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Just like having a clean car tends to make you drive more carefully and probably more fuel efficiently ....the power of the subconscious is an amazing thing !

Mercedes say your car is down roughly 30hp on 95 ron BTW.

Oh, and on the latest version there is actually a map for 102 ron as well apparantly, which is very rare.
 

John Laidlaw

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Mercedes say your car is down roughly 30hp on 95 ron BTW.

Oh, and on the latest version there is actually a map for 102 ron as well apparantly, which is very rare.
Indeed, as said earlier the tuned engines do notice, nay NEED the higher RON fuel...hadn't heard about this 102 though
 

gizze

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It was one of the mapping companies said they saw it in the software when writing remaps.

Not sure if anywhere still sells 102 though? Some Shell or was it BP stations sold it near racetracks.
 

Hi RX7

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You can still buy 102 around some track day circuits I believe, can't remember which but you can buy it.
I've always used V-Power since the early days when it was called Optimax and had my track prepared RX7 mapped to run on Optimax.
I've bought it for quite some time as I ran quite a few early Jap imports and they ran like a pig on standard fuel.
My other thoughts were the cleaning agents included in the fuel and run all of my petrol cars on V-Power.
Just recently I've switched to adding Hydra Fuels cetane booster and cleaner for my diesel vans and my Phaeton which works out a bit cheaper than buying V-Power diesel but is a bit of a frig having to syringe a certain amount in after a re-fill. All vehicles run just as nicely on the diesel additive.
 

MalcQV

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I've had a few performance cars that I have ran primarily on super unleaded. Mainly because of the additives and manufacturers recommendations. Sometimes it is just not possible to fill up with super unleaded.
I could not tell a difference between the two. Possibly flat out on a track you could.
As for £1000's on an MB. Not a 2004 CLK :D
I don't believe it can benefit in anyway to use super all the time. On occasion I'll run some through it. May just buy some petrol treatment from time to time.
 

gizze

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The problem with that is you often need a couple of tanks for it to switch back to full power, however the minute you add even a slight amount of 95ron it retards the timing. You need to make sure you have only 98 in there.
 
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shellnjohn

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  • Thread Starter
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Thank you all so much for your really helpful and eye opening advise and answers.
Very appreciative of the time many of you have taken.
This is a lovely forum
Many thanks Michelle x :)
 

John Laidlaw

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Glad to help and discuss Michelle....it's what we do! ( corny eh?)
 


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