Differences in fuel

[busby1971]

Ron Ron Ron

Ron Ron Ron

The Higher the RON the less engergy there is in a given fuel, RON relates to the ignite-abilty of a fuel and high RON fuels have less energy and ignite later in the engine cycle.

Cars will be designed to run on one or the other and using the wrong one in either engine type is just wasting money. The engine will be expecting a bang at a certain time and getting that bang at the wrong time will confuse it.

Just because something costs more does not mean that it is any better, Chris Hoy eats up his morning cereals and wins medals I certainly wouldn't be able to replicate this if I had the same breakfast without a bit of retuning.

With regards the OPs original question, buy branded fuel from a station close to a supermarket then you won't be paying over the odds and will think you're getting a good product.

 

[tats]

With regards the OPs original question, buy branded fuel from a station close to a supermarket then you won't be paying over the odds and will think you're getting a good product.

But will I actually be getting a good product? Or a better product?

 

[Goatherdingsplitter]

The Higher the RON the less engergy there is in a given fuel, RON relates to the ignite-abilty of a fuel and high RON fuels have less energy and ignite later in the engine cycle.

Cars will be designed to run on one or the other and using the wrong one in either engine type is just wasting money. The engine will be expecting a bang at a certain time and getting that bang at the wrong time will confuse it.

You're talking out of your exhaust!! RON is a measure of a fuel's ability to resist detonation (also called pinking or knocking) which is basically an uncontrolled explosion in the combustion chamber, instead of a progressive burn; if an engine is pinking and left unchecked it will ultimately lead to a very expensive repair bill. Higher RON fuels mean that timing can be advanced as opposed to being ignited later (retarded) as you state and it is the retarding of the ignition that leads to a reduction in power.
Some motorbikes, a fair few German cars and my car certainly are designed to run on either fuel and have a knock sensor to adjust the timing to cater for the fuel being used.

When I use supermarket 95 RON fuel my car logs ignition faults on the computer, when I run on 97/98 it doesn't - nuff said!

 

[busby1971]

You're talking out of your exhaust!!

I think you'll find I'm not.

Many high-performance engines are designed to operate with a high maximum compression, and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.

The Higher RON value allows a greater level of control over when the engine sparks and allows it to happen at an optimum point, less well tuned cars don't need to have such a high level of control and you can get away with cheaper fuel.

Original OP, Shell and Esso have a reputation to preserve so will probably apply a greater level of control over the product it sells.

 

[Goatherdingsplitter]

I think you'll find I'm not.

Many high-performance engines are designed to operate with a high maximum compression, and thus demand high-octane premium gasoline. A common misconception is that power output or fuel mileage can be improved by burning higher octane fuel than a particular engine was designed for. The power output of an engine depends in part on the energy density of its fuel, but similar fuels with different octane ratings have similar density. Since switching to a higher octane fuel does not add any more hydrocarbon content or oxygen, the engine cannot produce more power.The Higher RON value allows a greater level of control over when the engine sparks and allows it to happen at an optimum point, less well tuned cars don't need to have such a high level of control and you can get away with cheaper fuel.

Original OP, Shell and Esso have a reputation to preserve so will probably apply a greater level of control over the product it sells.

Glad to see you didn't repeat the rubbish from your previous post, but type some fresh tripe and half truthsDT_Xtremez_30:

To answer the area I've highlighted: Not all the fuel is burnt in the combustion process and in the modern 4 stroke engine, a complex relationship between ignition timing relevant to load and rpm, the incoming fuel/air mixture, temperature and valve timing in some cases, is managed by the ECU. Simply put: If you have to retard ignition because you use lower RON fuel (of the same density) THE POWER OUTPUT REDUCES.

I agree that cars designed to run on low RON fuel will get no benefit from using high RON (other than perhaps a placebo effect), but other than this you are mis quoting and contradicting the facts to serve your argument.

 

[Ex-Bay]

The Higher the RON the less engergy there is in a given fuel, RON relates to the ignite-abilty of a fuel and high RON fuels have less energy and ignite later in the engine cycle.

Cars will be designed to run on one or the other and using the wrong one in either engine type is just wasting money. The engine will be expecting a bang at a certain time and getting that bang at the wrong time will confuse it.

RON: http://www.petrolprices.com/about-fuel.html

Regardless of that debate, I understood that the modern engine has a lot of electronics to aid its ability to burn fuel properly and at the right point in the cycle..
Doesn't it automatically "compensate" for a different fuel then?

 

[Odie]

Doesn't it automatically "compensate" for a different fuel then?

It does within limits. A read of the guff I put in post 20 will tell you that. DT_Xtremez_15:But for you - if you put a lower octane rating fuel than the maximum the ignition/injection is set for, the knock sensors will notice the engine pinking/knocking and retard the ignition timing to stop the pinking. If the ignition/injection system is set to use a maximum of 95 RON, there's no point putting 97/98 RON fuel in it. The knock sensors won't see a problem, just that the engine isn't pinking, so it won't/can't advance the ignition to take advantage of the extra octane rating.

 

[Tubby]

If you have to retard ignition because you use lower RON fuel (of the same density) THE POWER OUTPUT REDUCES.

Which is why they sell those sh1t ignition advancer's and not ignition retarders to chav's with a equally crap cars.

 

[Hoof_Hearted]

Basically, Tesco, Asda, Sainsburys etc. are not main suppliers, it's a sideline for them, therefore the fuel they buy is the cheapest possible,

That isn't totally correct. Yes, Asda, Sainsburys, Morrisons, Waitrose - all will by their fuels at the cheapest price, and at the lowest possible (but still legal) specification. However, Tesco is a major shareholder in the UK's leading independent oil company - [www.Greenergy.co.uk Greenergy] - who make some quite decent fuel, especially if your car has to run on high octane super unleaded. Their 'Momentum 99' has been repeatedly proven to be the best fuel in the UK, outperforming the likes of BP Ultimate and even Shell V-Power.

it doesn't have the extra chemicals that will make your engine burn cleaner and leaner.

Generally fully agreed, to a point, save for the comments on Tesco Momentum 99 - which incidentally is the official fuel of the British Rally Championship.

But yes, all 'normal' supermarket fuels are less technically advanced than 'normal' branded fuels.

Esso, Shell and the rest of the forecourt fuel suppliers specialise in motor fuels, so they will buy a better product, you have to pay for it but you will be getting a better product.

That may be so - however, just because the sign on the petrol station forcourt may say BP or Shell or whatever - that doesn't necessarilly mean you will get BP fuel from a BP forcourt. There are exceptions - stuff like V-Power, Ultimate, Momentum - are all exactly what they say.

The owner of the local garage that I use for servicing refuses to use supermarket fuel as he swears it does your car no good in the long run.

On modern cars, then I'd generally agree. But the exception being Tesco Momentum 99.

But if you have an old shed of a car, then it would be fine running on dinosar p!ss.

 

[Hoof_Hearted]

I used to fill up, Volvo XC70 D5, at Morrisons, but was advised against 'supermarket' fuel by more than one mechanic. I now use Shell V-Power. Yes, it does cost a few pence more per litre, but the difference is noticeable. The engine runs quieter and pulls better.

That is a slightly different issue - Shell V-Power is classed as a 'Super Unleaded' fuel. So if your car specifically requires Super Unleaded, and you only use normal unleaded, even if it is one of the main brands - it will still do your car no good.

The best advice to generally start with - is RTFM - and then go from there. If your car specifically does NOT need super, then you are wasting your money on V-Power.

 

[Hoof_Hearted]

I have a Seat Leon Cupra (petrol, 1.8i) DT_Xtremez_30:

New shape or old? Anyway, I'm pretty sure you need to use Super Unleaded in that. I bet inside the fuel filler it says sommat like '98 RON'.

 

[Hoof_Hearted]

Generally, most cars sold in the UK are set to run on 95 RON unleaded, but many can also run on 91 RON jungle juice - often a label in the fuel filler will tell you what it needs. Some performance cars will use 97 or 98 RON super unleaded, but may also run on 95 RON fuel, my old '03 Golf V6 4motion being such a car - again there may be a label in the fuel filler flap telling you.

Hmmm . . . it depends. A lot of German cars need 98 RON juice, even basic shopping boxhead chariots. As an example, nigh-on ALL Volkswagen Group cars with FSI engines (even non-turbo) need 98 RON.

And just because you can run a 98 RON engine on 95 or 91 brews, that does not mean it is safe for your engine over the long term to use them.

A modern engine can usually run on the lower rated fuel because many cars nowadays have Knock Sensors fitted which "listen" for the on-set of knock or pinking. Once a knock sensor detects pinking it'll talk to the Control Unit which will often retard the ignition timing until the pinking stops with an associated reduction in performance and/or increase in fuel consumption.

You are perfectly correct that the ECU will adapt the engine to lower spec fuel - it basically does so to prevent any immediate damage. But by consistently using lower octane fuel in an engine designed for high octane, not only are you using more fuel, you are also causing more long term damage. Simply put, because the ignition timing needs to be retarded, that means that unburnt fuel is able to wash more oil off the cylinder bores for longer - thus causing acclerated engine wear.

However, putting a higher rated fuel in won't necessarily give an automatic increase in performance. If the recommended rating is 95 RON, then the ignition/injection is set to give its best using that grade of fuel and it can't adapt "upwards" above that setting to take advantage of the higher rating.

In effect, putting 98 RON fuel in a car that's set for 95 RON is really just a waste of money, but it won't do any great harm in doing so.

Agreed

 

[sp4rks]

Agree with the point about Tesco 'Momentum 99' stuff.

I've got a year 2000 1.8 Honda accord, it runs sweet as a nut on that stuff, but as it is so damned expensive i tend to only put it in every now and then.

As for V-Power and Ultimate i've never EVER noticed a difference, they say they are better but not from my point of view. Texaco stuff (i forget the name) is better than those two if you ask me but not as good as momentum.

i've even tried putting the octane booster in with v-power and it still wasn't any better than momentum.

i know which 'SUPER' unleaded i'll use.

 

[El_Boomo]

I notice a vast difference using v-power over 95 RON but to be honest the tesco stuff is just as good and a fair bit cheaper in most places.

Sainsburys 97 makes my car run like a bag of nails though.

 

[unruly1986]

Right, so at the refinery there's a fuel container labelled 'Tesco 97', one labelled 'Esso 97', 'BP 97' etc? Is there bollocks..!

The main thing to bear in mind is the RON of the fuel. If you have a remapped engine you will more than likely have to use 99 RON. Otherwise, the 95 RON petrol from Tesco/ASDA/BP will do just fine as it's all the same. My last car, a 2.5 turbo hot hatch ran fine on 95 RON fuel, so te person saying that a 1.8 Seat Leon needs 97+ rated fuel is wrong.

V power has additives but I imagine shell have their own refineries.

 

[ScoobTech]

This is from my observations from within my own car, which is fairly high performance, running and advanced ECU as standard with active knock control, to control timing and turbo boost.

I mainly put either V-Power or Esso super unleaded into it. so everything is fine, the boost gauge does what it does. If I need to fill up and super isn't available so I have to use branded regular, you can see the boost gauge hunting around and eventually drop onto a lower boost reading. I have only put supermarket fuel in it once, and when I needed to put my foot down it hunted around for a lower boost setting and pulled up a CEL (Check Engine Light), needless to say supemarket fuel has never gone anywhere near the fuel tank again.

When you go back to Super unleaded you can sea the ECU push the boost to known safe setting, then realising it hasn't started to detect knock start to push the boost up until it starts to detect it again.

The other things I have noticed in my old commute to work, I would get around 240 miles out of a tank on regular branded and around 290 miles a tank for Super.

But that is in my car, running a turbo. A car with a less advanced ECU will have less percieved benefit from super unleaded, as an increase in performance, fuel economy.

On my current long haul commute, around 600 miles a week, in my little diesel clio commuting hack, I haven't really seen that much difference between the advanced diesel and normal, either in power or fuel economy.

 

[Spearmint]

The main thing to bear in mind is the RON of the fuel. If you have a remapped engine you will more than likely have to use 99 RON. Otherwise, the 95 RON petrol from Tesco/ASDA/BP will do just fine as it's all the same. My last car, a 2.5 turbo hot hatch ran fine on 95 RON fuel, so te person saying that a 1.8 Seat Leon needs 97+ rated fuel is wrong.

It depends on what that particular engine was mapped on. I've known of at least 2 Skyline owners have their car re-mapped to run perfectly well on 95RON due to that being the most available fuel around their locality.

Just follow what the manual says if the motor is stock.

 

[Craig855s]

The answer to the OP is...Whatever the "recomended" fuel is (often writtin in the fuel flap) then that is what you shoud use. If it says recomended 97+ then you should be using 97+ (but can get away with 95, someone said it causes accelerated wear due to the retarding of the ignition...may be something true about that statement, but the engine would still do hundreds of thousands of miles running on 95 it's entire life)

As for diesel. you really dont need to mess around with the advanced ones. Just put plain vanilla diesel in (if you own a particularly old diesel then you may be able to run veg oil in it)