Why do people buy high octane petrol?

[Simon]

A bad sensor will cause an NA to det.

 

[ultralaser]

Sorry to raise a thread from the past, but I always wondered if the "premium" fuel made a difference, so today I tried it. For me I ended up getting around a 16% MPG increase from Esso's higher end Unleaded. It was a lot of motorway driving (basically setting the cruise control at around 70 and using some standard supermarket fuel on one leg of a trip and the Esso stuff on the return. It's not a turbo nor does it say anywhere in the cars handbook to use higher RON fuel. But it really did make a difference. Just wondering if anyone has a link to some more 'scientific' testing on this? Cheers, UL.

 

[Jonnycoupe]

Google is probably good to check the height above sea level between the start and end of your journey...

 

[silversurfer]

Sorry to raise a thread from the past, but I always wondered if the "premium" fuel made a difference, so today I tried it. For me I ended up getting around a 16% MPG increase from Esso's higher end Unleaded.

What engine gains that much, ideally a lot more data would be recorded and it'd be possible to see where any gains were coming from

 

[LeeUK]

You would probably need to flush through a few tank fulls for it to make any difference.

 

[Meridian]

You'd also need a computer to drive the car, because you can easily make that difference by changing your driving style - which is almost certainly what actually happened.

 

[Overlag]

You'd also need a computer to drive the car, because you can easily make that difference by changing your driving style - which is almost certainly what actually happened.

100%. Literally the only way to test this would be on a dyno running a computerised program.

 

[Nasher]

If your car's manual doesn't say you need high RON, then you'll see no benefit from it. It's mostly high performance NA that want it due to the high compression. Most engines are 7-9:1, that doesn't need premium.

The higher the RON, the high the temperature it takes to burn the fuel. So on a lower compression engine it can be a bad thing.

 

[Mulder]

Because it makes me feel better paying through the nose and getting less than 20mpg on average.

That and my car says it needs it, and it's always been run on it.

 

[robj20]

Tends to have a better additive package as well, better and more detergents and lubricants.

 

[Nasher]

Tends to have a better additive package as well, better and more detergents and lubricants.

But no one has actually managed to verify that, only octane booster

 

[bainbridge]

In Germany it was called "Shell 100 Octane Racing Fuel".

Compulsory to fill up with that cos it's for racing

 

[robj20]

But no one has actually managed to verify that, only octane booster

Your right Shell must be lying when they say it has cleaning additives and lubricants.

 

[killsta]

So does Tesco apparently, and no doubt others too.

https://www.tescopfs.com/news/quality-fuel-guaranteed

Is it just that Shell sing the loudest about keeping your engine clean?

 

[NewGamer11]

My car is designed to run on 95 RON so I just use the standard. No point buying premium.

 

[Rybo89]

I rather run out of petrol than put anything other that Tesco99 or Vpower in my car.

95 would make it run like an utter dog. Once tried BP97 and it made it run worse than a utter dog.

 

[Dogbreath]

My car is designed to run on 95 RON so I just use the standard. No point buying premium.

Most cars are designed to cope with 95 Octane fuel, but that doesn't mean it wouldn't run better on 97/98. Whether any improvements are worth the extra outlay is the question.

 

[crinkleshoes]

Genuine curiosity here, not a rant. I notice a lot of you posting that you buy V Power or Super whatever petrol, but I can't see what you gain from it? By my understanding, your engine will either knock with a given fuel or it won't, and all modern petrol road cars are designed with 95 octane unleaded in mind because that's the "normal" fuel sold at petrol stations. So if it can use 95 without any problems, what do you gain from paying more for higher octane fuel? There's no efficiency savings, no power boost, just a lighter wallet.

Am I wrong?

Not all are tuned for 95... my Porsche detunes itself if I stick 95 in. Reduces the power and torque a bit and I can feel it... also details it in the owner's manual... I imagine it has a knock sensor or something and adjusts the timing relative to the fuel.

Also... VPower and similar fuels have cleaning additives that have a genuine benefit to engine longevity... it's not just marketing BS like some used to think.

 

[NewGamer11]

Most cars are designed to cope with 95 Octane fuel, but that doesn't mean it wouldn't run better on 97/98. Whether any improvements are worth the extra outlay is the question.

I think my manual specifically says not to use higher quality octane as there is no benefit.

 

[agw_01]

I've seen first hand what effect running on V-Power can do to an engine. I've compared 2 identical engines with similar mileage, one ran on V-Power in my ownership for 40k miles and the other with unknown history. If anything, the unknown engine had less miles than mine.

My engine had significantly less carbon build up on the piston crowns (to the point you could see parts of the piston itself), the valve seats took considerably less lapping to get to a point where the valves would seal and when both sets of injectors were sent away for cleaning, my original set saw only a slight benefit (1-2cc/min) compared to the unknown set which saw around a 35-40cc/min flow improvement.

These were Rover T16 Turbo engines with a factory map designed for 95 ron fuel. I had no reason whatsoever to run V-Power other than for its cleaning properties.