Anyone using high octane petrol and notice any benefits?

LightFlare

Used to use it on my highly modified Subaru, about 1 in 3 fill ups or prior to a long run

MPG was approx 10% higher on a long motorway run - but probably not enough to offset the added cost.

Was def noticeable if constantly using the “lesser” fuel

flaneurs_lobster

WellKnownSid said:

Car_54 said:

Gobsh said:

My Citroen is still in warentee and service centre is recommending fuel Additives???

Does the service centre happen to sell the recommended additives?

“Completely by chance, as luck would have it, we just so happen to have one extra large bottle in stock… which we can sell to you at the old price before prices go up on Monday…”

"SNAKE OIL, GET YER LUVERLEY SNAKE OIL 'ERE. ONLY A TENNER A PAHND"

Mildly_Miffed

Higher octane may have a benefit if the base ignition map and boost are set to take advantage of it - which few unmodified European-market cars will be.
If yours is one of the exceptions, then it'll generate more power at full throttle, when the boost and/or ignition would be pulled back to prevent pinking.
Whether you need more power while driving in a sensible manner on the road is a different question.

It's very unlikely to produce better fuel economy. If it does, that extra economy is very unlikely to outweigh the extra cost.

The differing levels of ethanol are mostly a red herring, unless your vehicle is stored over winter in a damp atmosphere with a fuel system that easily vents to the atmosphere (in which case, evaporation of the fuel will be a bigger problem). Every vehicle sold new in the UK or elsewhere in Europe since 2009 must be fully compatible with E10. Most older vehicles are, too - unless they have very low quality fuel hose, which should be replaced with better stuff anyway as age will have taken a toll.

Premium diesel provides zero functional benefit in any vehicle.

Bigwheels1111

I use premium diesel, only because it’s cheaper than standard diesel at Costco.
In winter I add Mannol cutane booster.
The car starts smoother & is quieter.
Moves off smoothly, less hesitant.
I don’t think I get better mpg.

Mildly_Miffed

Bigwheels1111 said:

I use premium diesel, only because it’s cheaper than standard diesel at Costco.
In winter I add Mannol cutane booster.
The car starts smoother & is quieter.
Moves off smoothly, less hesitant.
I don’t think I get better mpg.

The single grade of diesel sold at Costco is the exact same diesel you'd buy anywhere else, shipped by the same pipelines from the same couple of refineries that serve the entire country to the same small number of regional distribution depots. It has to conform to the same fuel quality standards as any other fuel - EN590 - which specifies a minimum of 51 cetane. That standard is identical for all road diesel, "normal" or "premium" - the difference is purely marketing.

As with all other UK fuels, it has a small bucket of virtually homeopathic brand-specific additives tipped in at the time the tanker is filled for delivery to the filling station. 

Any perceived benefit in noise or starting or refinement or hesitation is going to be purely anecdotal, and wouldn't stand an actual blind trial.

I VERY much doubt any higher cetane will make the slightest difference in combustion in any road engine.

forgotmyname

fatbelly said:

I do occasionally add Redex.

I think there is some evidence of benefit and so at £2.50 a shot, I give it a go.

https://youtu.be/03nL8Z0dRkI

Slightly misleading video,  put most cars on a rolling road and the first runs will often be down on power because they are
rarely driven at high rpm so the ECU calibrates itself for the conditions.

They did another test using redex or similar and only did a single rolling road run and then took it around the track to allow
the redex to do it's thing. Driving at higher speeds and harsher acceleration than it would have on the road and they are
surprised the power increased. It would have increased without the additive.

B0bbyEwing

I tested this out some time ago. I'd been running on 'normal' Shell fuel. I then started filling up with V-Power (all petrol btw). 

Now where some people go wrong is they do 1 tank full, maybe 2 & then try to draw conclusions from it. I ran it for getting on a year IIRC.

Noticed zero difference ... and I was clocking my MPG calculated manually, not by an on board display. I was fuelling at the same station each time & stopping at the first click each time. Using the same pump each time when possible although it wasn't always possible obviously. 

My MPG didn't really change. The performance wasn't noticeably different. Maybe something was going on positively that wasn't visible, but I've no idea.


Now where I have noticed a difference in the past was using Miller's diesel additive when I've had a diesel car. Better MPG. 

Other than that, no, no different.

born_again

Difference is your pocket is lighter... 

Goudy

The higher the octane rating of the petrol the more it can withstand compression before it ignites without a spark. 
This type of ignition under pressure is call auto ignition and can cause a car engine to knock as the fuel pre ignites before it's meant to.

Most modern cars have knock sensors and can, to some extent make use of this type of fuels resistance to auto ignition. On your average car the results are usually negligible though.

Higher performance engines that utilise higher compression ratios tend to make better use of it.
They can time the spark better for optimum performance before it self ignites under high pressure before the spark.

Those silly bhp figures quoted by the likes of Abarth for the small turbo charged 595's are set on higher octane fuel and it tells you in the handbook to achieve those figures yourself you need to use 99+ octane fuel.

These premium fuels also have various additive packages added to them.
These are broken down into two, often a nitrogen based cleaning agent and friction modifier agent.
Petrol companies make certain guarded claims about the usefulness of these packages. There is some truth in what they claim, but you make your own mind up how much that benefits you and your car.


Diesel engines actually utilise this auto ignition of the fuel.
There is no spark to ignite the fuel, it goes bang under pressure.

Diesel fuel then has a rating for it's combustion speed, so how quickly it burns once it self ignites.
This rating is the cetane rating. The higher the rating the more quickly it burns.

The engine doesn't need to be able to make use of it by altering the ignition timing. Unlike a petrol engine that may alter it's spark to make better use of the higher octane fuel, a diesels combustion on higher cetane fuel is pretty much the same as normal fuel.
It doesn't really alter the point it combusts, it's just the speed the burns is quicker with higher cetane fuel.

This is a little easier to understand and the results of higher cetane are also easier to figure.
Apart from the advantages of the ability to burn quickly at the precise time, as it burns quicker it can lead to a more complete burn.
Soot is unburnt fuel, so having the ability to quickly burn the fuel generally leads to a more efficient combustion with less soot.
As more of it is burnt, so you get more out of it.

Diesels tend to knock anyway but the quicker burn tends to reduce this knock, often it's quite noticeable particularly when the engine is cold.

The additive they add to diesel to improve it's cetane rating is 2-ethylhexyl nitrate (2-EHN).
It's generally quite cheap (you can buy it neat in drums) and it doesn't take much to improve a tank fuel of diesel enough to perhaps make it noticeable in terms of knock.

Nearly every over the counter diesel fuel additive will be made up of a carrier fluid, some sort of perfume to make it smell nicer (not Chanel) and 2-EHN.
They might also have some cleaning agents and friction modifiers, again claims of these cleaning and friction agents are taken with a pinch of salt.

So basically your average petrol car might only make a negligible difference on higher octane fuel, a higher performance car might make better use but all diesels will more than likely make some better use of higher cetane diesel.
If they are worth it or not is another question though.  





 

forgotmyname

2-EHN can degrade the quality of the fuel and increase emissions. Seem to remember adding too much
has the opposite effect.  It pops up every now and then as a newly found additive that everyone needs
but then the negatives make it not worthwhile for most people.