superunleaded fuel

[bonecracker]

My C200K has recently had very poor petrol consumption, a very experienced mechanic said that super unleaded feul might make a difference. What is your opinion?

 

[stwat]

All i can say is, super unleaded costs a lot more and i cant see how it will give you better consumption. Have you had your car tuned? That should be the first step to getting it running better.

stu

 

[squealinneil]

stwat,

You are wrong! All petrols are not all equal, far from it.

Have you ever bought a tank of super unleaded?

Yesterday I filled up at a Shell station. Normal unleaded was 83.9 & super was 89.9. I bought 55 litres so spent about 3.30 extra on the super. To recoup this enormous additional outlay I need to get about 24 miles more per tankfull of super, which I easily achieve.

It is actually CHEAPER to use super because my cars go further on each tankfull, they also run stronger, faster and are more responsive (there's a pronounced performance difference in my 190E 2.5-16). As well as giving superior performance & economy due to higher octane (more bang for your buck), both Shell & BP super fuels also have much higher detergent content keeping everything shiny, clean & gunk free.

I'm always amazed when I see people in expensive high performance cars filling up at supermarket petrol stations, presumably to save the 2 or 3p per litre. NO NO NO NO NO!

Would you put cheap oil in your car, do you buy cheap tyres, do you buy beer based on the price? Do you buy your groceries at Lidl? - after all, food is food, isn't it?

The FIRST thing bonecracker should do is fillup with super, check the fluids, tyres etc & when the car is good & hot take it out for a good, hard, 40 mile Italian tune up, close to red line up through the gears, to blow it out.

If you think I'm wrong then spend a couple of quid extra next time you re-fuel & try the super unleaded. I guarantee I'm right.

 

[200e]

Agree with you squealinneil sounds as if stwat is penny pinching I run a 200e and noticed the difference in performance with the super unleaded and I get around 28- 35 depending on my journeys apposed to sluggish response an the accelerator and a mileage of between 25-30 so go for the super unleaded after a thankful you will see the difference

 

[jberks]

Seems like this is a subjective point. I have tried super unleaded for a couple of weeks on my 600 mile per week commute. I noticed a small performance improvement but bugger all difference in fuel consumption, maybe 1mpg, but I can make more than that up by turning off the air-con or not driving like a prat.
If you can get such a drastic improvement by switching to super - which is only fractionally more potent, I suspect there is something else wrong somewhere and you're only actually getting what you should get with conventional fuel, by compensating for the fault with better fuel.

There is a difference between fuels though, my car seems to run better (inc MPG) on BP than esso - perhaps your supplier's unleaded is crap?

 

[mjtray]

As other posters have said its a very subjective subject...From my experience, higher quality fuels such as Optimax can make a big difference in older cars, ie pre-cat.

I had 1982 Porsche 911 which ran sooo much better on Optimax than anything else.

My motorbikes also ran much better, whereas on Supermarket fuel they ran likes dogs.

However, when it comes to post cat cars I have found all unleaded be it supermarket or branded makes no difference. I have always tended to put injector cleaner in my cars every 5000 miles, as its true, Supermarket fuels have less detergent in them than branded fuels.

Maybe the poor performance on your C200K is down to gummed up injectors.....try running a tank full of fuel through the system with some injector cleaner added and as other posters say....give it an Italian tune up, ie take her right up through the rev range and give her some stick to blow out the cobwebs

 

[ant500sl]

A little technical explanation:

Super unleaded has a higher octane rating i.e. 97 or 98
Premium has a rating of 95

The number refers to in simple terms the fuels resistance to knock or detonation at high compression. Basically this is where the whole mixture explodes of its own accord and eventually burns a whole through your nice shiny aluminium piston.

Older performance engines were generally designed to run on 4 star at about 98 octane. This means if you use 95 premium you will experience lower power, higher engine temperatures and detonation in extreme cases with ultra high performance engines. Likewise using something like Optimax will allow the engine to perform as it should.

Newer engines have things called knock sensors which detect detonation and retard the ignition to allow the engine to perform to its maximum on any given fuel. When using high octane fuels the engine will advance the ignition to the maximum point possible before knocking occurs and give in some cases a notable improvement in power. How much is entirely dependent on the car and the fuel.

My own rule of thumb is to use super or LRP in older high performance engines unless otherwise specified. Not worth spending the extra for a conventional engine I would say.

With modern engines it is entirely a matter of choice, but probably best to stick with a reputable name in my opinion as some of the spot bought fuel out there can be quite ropey. Personally I have never noticed much difference between fuels unless you compare something like Optimax to the lowest grade of supermarket fuel imaginable (Which I believe is what Shell actually did to show the performance gains).

If you want some fun you could always fill up at your local airfield on 103 octane. Only suitable for race use with pollution and tax implications!

 

[mlc]

my two pennies worth!

This subject has been discussed many times and so many people have said that the expensive fuels are better that I decided to give it a go. We are currently running both our main cars on BP's super unleaded (optimax?). The only thing I can currently say with any confidence is that it costs more! I look forward to been proven wrong but at the moment the fuel economy isnt showing any difference and the performance seems the same. I suspect that the high detergent levels etc would help if you had a problem, but if everything is running ok in the first place what improvement can it give. The extra cost of the fuel means that you require at least a 5% reduction in consumption just to cover costs. I really think that if anyone could offer a simple cost effective method of improving fuel economy by 5% they would be on a winner - and the Government would offer a tax break to get us all to use less fuel!

I could of course be proven wrong.

Mark.

 

[stwat]

Right, having read some of your answers, i thought id give it a go and tonight i fillled up with bp superduper rocket fuel and straight away i can say that the performance is noticeably better. It starts to pick up much sooner than before. But weather i get better mpg is still to be seen. Due to the higher price i very much doupt that it will work out cheaper than a tankfull of unleaded overall. But only time will tell.


As for penny pinching!!!! I think not. If i was a penny pincher i dont think id be driving a ****** automatic merc do you??!!!??? If i had my way id be driving a bleedin 500E and fcku the mpg

As it goes, a 300ce is next on my list Pref a 24V :wink:

Stu

 

[squealinneil]

stwat,
How much extra did you pay for the tankfull of high octane & how many extra miles do you need to get to break even? I've got a 190E 2.5-16 with (I think) a 70 litre tank. How much does yours hold?
If you don't get enough extra miles from the better fuel do you think the way the car drives has justified the extra expense?
Pls. keep us posted on the outcome.

 

[mr. shr]

So are all supermarket fuels bad? Are some worse than others?

I always use supermarket fuel (mainly Morrisons) but if I want to try the super stuff do I need to let my current tank run near enough empty before I fill up?

 

[squealinneil]

Mr Shr,
some say it doesn't make much diiference depending on the age of the car. What yr. & model do you have?

 

[mr. shr]

Mines a W208 CLK 320 from year 2000.

It's a fantastic engine. Am I doing it misjustice by filling up at Morrisons?

 

[benzo]

Mines a W208 CLK 320 from year 2000.

It's a fantastic engine. Am I doing it misjustice by filling up at Morrisons?

YES!

 

[bigt]

Here on the Humber estuary we have two refineries, one owned by Total and the other by Conoco. It is an education seeing what tankers go in and collect their cargo from the refinery loading points, I have seen tankers from Shell, Esso, Total, Fina, Sainsburys, Morrisons, Tesco and BP. Around the UK there are refineries at Ellesmere ( Shell ) Southampton (BP), Purfleet ( Esso ), Grangemouth ( BP), Milford Haven ( Texaco/Gulf ).

All so called branded fuels are bought from the most local points - lets face it, no one is going to ship a full tanker load of shell petrol from Ellesmere up to scotland, the cost would be immense, so it is all sourced locally. Raises some interesting questions though - are they all the same or not ?????????????

Merry X-mas all.

 

[stwat]

stwat,
How much extra did you pay for the tankfull of high octane & how many extra miles do you need to get to break even? I've got a 190E 2.5-16 with (I think) a 70 litre tank. How much does yours hold?
If you don't get enough extra miles from the better fuel do you think the way the car drives has justified the extra expense?
Pls. keep us posted on the outcome.

Well, it cost me a few pence over £40 to fill up with BP ultimate and i got 206 miles out of that tankfull.

With normal unleaded it costs me around £35 to fill up and i would normaly get around 180 to 190 miles from one tankfull.

Im to ****ed to work anything out at the mo, so il just leave that to you..LOL sorry.

Stu

 

[tom7035]

Hey, this is all a far cry from the days of the old side-valves, when a gallon of paraffin in with 5 gallons petrol helped us through the fuel rationing!! (God, I'm dating myself AGAIN!)

 

[bigt]

fuel type

I usually fill up with Sainsburys normal unleaded and often do a journey of 310 miles round trip. Usually I get about 30 to the gallon on this trip.
Today , for the first time I have tanked up with Shell Optimax and am doing the journey again over the weekend - will report back the results of this super laboratory controlled scientific experiment in the new year.

Happy new year all
Trev

 

[SLinKyjoe]

I need the answer to this question.

Is supermartket fuel better than Shell optimax or BP Ultimate or not.

You see being a yorkshire skinflint i fill up with sainsburys normal stuff. thats coz i shop ther and get 5p a litre off. which means if it were possible to fill the whole 70litre tank i would get £3.50 off the price. at the mo it would cost £55 to fill the tank with sainsburys and then get £3.50 off, and £60.50 with Shell optimax. Local fuel prices as of 27th Dec.

The Local Shell garage that i used to use (And I always filled up the Scooby with Optimax) thought it was a good idea to clone my credit card and buy stuff on it. The credit card firm caught them and informed me but it soured my opinion. The scooby was expecting 98ron where as the New Merc only expects 95Ron so will it really make that much difference.

Might do a test myself but cant be bothered at the mo. The SRS warning light is on so I dont really want to drive about if I can help it.

I await the results.

 

[Terminator]

I have recently completed a comparison of super unleaded (BP Ultimate)versus (Normal BP) unleaded and can conclude that super unleaded gives me approx 10% improvement in fuel economy (350 miles per tankful compared to 315 per tankful. I do a 100 mile round trip each day including town, B Road, A Road, and Motorway which provides a good mixture of different driving conditions. The car feels much more responsive and smoother using BP Ultimate over standard unleaded imo.

P.S. Stwat, your fuel consumption seems very high?