"Better" Fuel

Do you use the Super Unleaded or the normal stuff?

  • I use either /or depends on what's available.

    Votes: 8 24.2%
  • I always try to use the 'Super' fuel - the car runs better

    Votes: 14 42.4%
  • I never use the 'Super' fuel, no benefit and costs more

    Votes: 11 33.3%

  • Total voters
    33
  • Poll closed .

MBDevotee

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Hi,

I was reading my manual for the car (51 plate 320 petrol) and it said the car must have 95 octane petrol to run properly.

However later in the manual, it said 91 octane could be used as "sensors in the engine will adjust to the lower octane to prevent damage".

I take it then the car has a "knock sensor"....

So with that in mind, I did about 1000m with 95 octane 'regular' unleaded. I averaged 30.6mpg over this time (pretty impressive I thought for a 3.2). I then ran the car to almost empty and filled with Shell "V-Power" which claims all sorts of benefits but costs 95ppl rather than 89ppl.

Having now covered a further 350m the computer is reading 32.8mpg.

I am pretty sure I have been on the same sorts of roads etc so, I do seem to be getting better mpg from the higher octane fuel, I also think (and is this wishful thinking?) that the car seems to have more power and runs smoother - does anyone know if a proper scientific study has been done on these fuels for a normal car as opposed to Mitsi evo's etc and were the results conclusive?

Does anyone else use the "super" unleaded, and if so do you think it's worth the extra money - certainly if my experience is anything to go by its extra cost (7%) is more than matched by the extra mpg (also about 7%) and if it means the car also runs better I would stick with the better fuel -

Thoughts?
 

5907

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I also seem to get better MPG when using BP ultimate in my 1995 E280, so much so in fact that it offsets the higher cost per litre.
 

Miffy

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I have already said in another post re this question. my 02 clk 320 cab did about 28. mpg whilst i had around 31 using v-power. the journey was 100% the same, a round trip from London to Newcastle. thats about 750 / 800 miles for each weekend.
 

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I have been using VPower unleaded in my W220 S320 since November exclusively (apart from one fill of BP Ultimate). On average I do around 70 miles per day and since using this fuel I am seeing around 30mpg. The car runs smoothly but always had and its a long wheelbase SClass so takes a long time to get moving at the best of times. I am not sure that the petrol has made any difference to overall performance. I have done quite a bit of research on this and there appears to be no evidence supporting consistent long term benefits (apart from to the chancellor) of using this stuff. My reasons are simple, I use it because it is supposed to have greater concentrations of detergents and lubrucating agents in the fuel.

Although I would have thought that "normal" Shell 95RON also has these.

I am thinking of switching back as its getting a pain to always try and find a Shell garage when I need to fill up. I cant say I have experienced such a major difference that makes me think that its worth sticking with it forever.
 

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Our cars all come down the same production line, and are shipped to all parts of the world.

Some countries only have access to 91 ron fuel. On all of our standard engined cars it has been shown many times on here and in the press, that using 98 ron is a waste of money, as the engine cannot benefit from this higher octane fuel. In the olden days we could alter the ignition settings for these different fuels, but these days our cars will adjust down to 91 ron, but care should be used when using it and the max performance of the car should never be used.

The reason for this is the lower the octane, the more prone they are to poor detonation, this can be heard as a tinkling sound when accelerating, and is commonly known as pinking. Pinking is harmful to the pistons,, and can cause piston failure.

Using a fuel with a higher octane than the engine can burn is money down the drain
 

sweeper

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Our cars all come down the same production line, and are shipped to all parts of the world.

Some countries only have access to 91 ron fuel. On all of our standard engined cars it has been shown many times on here and in the press, that using 98 ron is a waste of money, as the engine cannot benefit from this higher octane fuel. In the olden days we could alter the ignition settings for these different fuels, but these days our cars will adjust down to 91 ron, but care should be used when using it and the max performance of the car should never be used.

The reason for this is the lower the octane, the more prone they are to poor detonation, this can be heard as a tinkling sound when accelerating, and is commonly known as pinking. Pinking is harmful to the pistons,, and can cause piston failure.

Using a fuel with a higher octane than the engine can burn is money down the drain


Higher octane fuel will equal better performance, the ignition system can also adjust for the higher octane, advancing the timing just short of pre-ignition knock is the most efficient, whether you actually can measure this difference in normal driving i doubt, as no two journeys are identical and the difference is only small, so the benfit can only be measured over a long time and to be honest i really couldn't be arsed with all that, so i use whichever fuel is the best price, in Germany you can get higher octane for the same price (measured in ROZ not RON) so when we are over there i get that, I do check the MPG every now and then and so long as it is around the right mark and the engine is running ok i don't worry about it, driving habits can have a much bigger impact on MPG, but how boring is all that? life really is too short to worry about the odd 1-2 mpg, i once new a guy who wrote down every time he put petrol in his Vauxhall Nova 1.2l, how much and how many miles then worked out what mpg he got! Why? I purely check mine once in a while, usually when we do a long trip, just as a reference that may point to a problem.
 

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Higher octane fuel will equal better performance, the ignition system can also adjust for it.


No it will not, thats impossible, there is a rated output for any engine, and you will not improve on that by using a higher octane fuel

There is a lot of official info on the web on this subject
 

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Putting the potential performance impact to one side, is it not of benefit to use these fuels for their additional additives?

I agree that using them in a normal engine seems to make little or no discernible difference in performance but in my case I use them purely for the "alleged" cleaning properties.

My local indi reckons this practice is a waste of time and money as the same additives exist in the 95RON fuels from the likes of BP and Shell.

What do you think?
 

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Putting the potential performance impact to one side, is it not of benefit to use these fuels for their additional additives?

I agree that using them in a normal engine seems to make little or no discernible difference in performance but in my case I use them purely for the "alleged" cleaning properties.

My local indi reckons this practice is a waste of time and money as the same additives exist in the 95RON fuels from the likes of BP and Shell.

What do you think?

One thing that has been said on here many times is that the super fuels can help clean the float gauges, but the same effect can be got by using a tin of REDX or the like, to clean the injectors
 

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Thanks Malcolm. Blimey I have just noticed your post count!! Thats a pretty amazing achievement over 31,000!!!
 

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Thanks Malcolm. Blimey I have just noticed your post count!! Thats a pretty amazing achievement over 31,000!!!

I do not think about it any more, there are another 25.000 floating around the world elsewhere
 

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these fuels were tested on tv a few years ago with a variety of cars. unless you have a high performance highly strung engine (they used an impreza turbo! surprised it ran long enough!) they make no difference at all! even the impreza only gained about 4bhp and it was around 320bhp to start with (minor mods somewhere, cant remember what though)
it is true though that the car alters its timing to suit the fuel to the point just before detonation (pinking). as someone already pointed out, its sensed by the knock sensor. the higher the octane, the more timing advance you can run with (hence benefit on performance engines) as the higher octane fuel burns slower than lower octane stuff. anyone who remembers having their engine re tuned for unleaded when it first came out will remember having their timing retarded slightly to avoid pinking! although in this case it was also to help protect valves and valve seats. and i did try a few fords with unleaded for a few miles on unleaded with the timing set for four star. every one of them suffered detonation under a decent load ie steep hills etc! I hope all this bulls**t is of use to someone! if its not, i need to get out more!!!
 
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MBDevotee

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  • Thread Starter
  • Thread starter
  • #13
My results after 2000 miles (so hardly a really scientific study)

Was chatting to the guys who are going to do the LPG conversion on the car for me soon.

They said that the Merc 6cyl is probably the best car in the world to convert, and all of the Merc's convert well because of the engine management. Apparently the engine adapts to the octane and quality of fuel being used on almost a constant basis. It advances the timing in tiny stages, until it detects pre-ignition, and then retards it ever so slightly - apparently it does this every single firing stroke, until it finds a happy setting, but it doesn't just then set it, it constantly re-calibrates this, so it is constantly running as efficiently as it can.

I asked whether this means putting Super-unleaded in makes a difference - they reckon it certainly would, and my findings so far are thus...

700 miles on std unleaded - averaged 34.6mph and 30.6mpg
700 miles on Shell V-Power 99 octane - averaged 34.7mph and 32.8mpg
650 miles on Sainsburys Super Unleaded 97 octane averaged 34.6mph and 31.4mpg

Now I realise that this isn't scientific, and the MPG is only off the computer - however it certainly seems to me that the higher the octane the more MPG I get - I am now going to run a while on the Sainsbury's stuff until I get converted as it's only 92ppl and that's giving me the lowest pence per mile of any of the three options. Once I get converted and am running on LPG (100 - 103 octane) then I will switch to using the Shell V-Power as the difference in octane's is least.

I also noticed that the vote on the poll certainly seems to favour the dearer fuels.
 

nickcc101

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Putting the potential performance impact to one side, is it not of benefit to use these fuels for their additional additives?

I agree that using them in a normal engine seems to make little or no discernible difference in performance but in my case I use them purely for the "alleged" cleaning properties.

My local indi reckons this practice is a waste of time and money as the same additives exist in the 95RON fuels from the likes of BP and Shell.

What do you think?

Same additives in Shell ULG and SULG. Injected whilst tanker loading takes place, all automated. Oil companys don't share additives only the base product (petrol/diesel).
 
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Alex M Grieve

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Same additives in Shell ULG and SULG. Injected whilst tanker loading takes place, all automated. Oil companys don't share additives only the base product (petrol/diesel).

Entirely agree - but they all struggle to differentiate themselves from the others in this market.

I remember working for Shell in the mid 1980s when they were putting in an additive (dosing was more of a bucket and spade job in those days). A BP distribution centre called me in error to ask about some side effects that one of their drivers had experienced when dosing his BP delivery vehicle - the identical side effects to overexposure to the Shell additive - which suggested to me that they were using the same stuff!
 

PJayUK

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So are we saying that the only difference between Shell V-Power and Shell "Ordinary" 95RON is the octane level?

According to the Shell site:

Shell V-Power : Formulated for powerful cleaning

Shell V-Power contains powerful cleaning agents, designed to prevent the formation of power-robbing deposits which can impact on responsiveness. Shell V-Power is formulated to help remove existing deposits that other fuels may have left behind, to help new engines run smoothly for longer, and to help rejuvenate older engines.


Now this is very interesting, if we are saying that the above also applied to the regular Shell unleaded fuel.

Thoughts guys?
 

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So are we saying that the only difference between Shell V-Power and Shell "Ordinary" 95RON is the octane level?

According to the Shell site:

Shell V-Power : Formulated for powerful cleaning

Shell V-Power contains powerful cleaning agents, designed to prevent the formation of power-robbing deposits which can impact on responsiveness. Shell V-Power is formulated to help remove existing deposits that other fuels may have left behind, to help new engines run smoothly for longer, and to help rejuvenate older engines.


Now this is very interesting, if we are saying that the above also applied to the regular Shell unleaded fuel.

Thoughts guys?



We know that 98 has cleaning additives and we tell people to use it to clean up tank floats and injectors, so use it once in a while,. and go back to your normal 95
 

nickcc101

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So are we saying that the only difference between Shell V-Power and Shell "Ordinary" 95RON is the octane level?

According to the Shell site:

Shell V-Power : Formulated for powerful cleaning

Shell V-Power contains powerful cleaning agents, designed to prevent the formation of power-robbing deposits which can impact on responsiveness. Shell V-Power is formulated to help remove existing deposits that other fuels may have left behind, to help new engines run smoothly for longer, and to help rejuvenate older engines.


Now this is very interesting, if we are saying that the above also applied to the regular Shell unleaded fuel.

Thoughts guys?
Unable to speak for shell Vpower as i left Shell 12 years ago (after 26 long years). There was only one mogas additive tank for all grades of Shell petrol and one for diesel. As for other companies using each others additives this does not happen (remember formula Shell when only Shell petrol was affected). Still a dirty word at head office.
 

Miffy

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We know that 98 has cleaning additives and we tell people to use it to clean up tank floats and injectors, so use it once in a while,. and go back to your normal 95


The owners manual for my car says that I should only use normal Unleaded in an emergency and that I will suffer loss or performance and MPG whilst using this fuel type.
 

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As an ex petrol pump attendant of sorts, I can tell you that 95 or 98 RON fuel carry the same additives. The only advantage to be had from the higher octain fuel would be if the engine was remapped to take advantage of this.
You are then stuck with having to find a petrol station with super unleaded.
We had a saying for drivers who insisted on filling with s/u -

Give the cat a goldfish :confused:
 


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