What petrol should I use?

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I'm going to be doing alot of miles on the motorway over the next few weeks.
I have seen advertising that says if I use Super Unleaded (98 RON) I will get better performance than Regular Unleaded (95 RON) and better fuel efficiency.

So my question to you is: Is it worth paying out an extra 5p per litre for the super unleaded?

I don't know if it'll help, but I have a 1.4L Volkswagen Polo with a 45 Litre (approx 10 gallon) tank.
 
I used Optimax for a while over the summer. I got slightly better fuel economy, but I don't know if that was down to the fuel, or the type of driving I was doing. (I was doing more longer runs than usual)

Any test of different fuels that I've seen seem to say Optimax, BP Ultimate etc, work better on more powerful engines. I don't know if you'd notice any difference. But there really is only one way to find out, and that is to try it for yourself.
 
IMTDS
I'm going to be doing alot of miles on the motorway over the next few weeks.
I have seen advertising that says if I use Super Unleaded (98 RON) I will get better performance than Regular Unleaded (95 RON) and better fuel efficiency.

So my question to you is: Is it worth paying out an extra 5p per litre for the super unleaded?

I don't know if it'll help, but I have a 1.4L Volkswagen Polo with a 45 Litre (approx 10 gallon) tank.
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No.

Super Unleaded is a more stable fuel (higher octane rating = more stable). Your car will see NO performance benefit at all as, though it will advance the timing, it can't use the fuel as effectively as it can use 95RON. Cars with barking mad engines need 98RON because it's more stable than 95RON, so blows up in the right place, rather than blowing up early (preignition/knock) because the whole engine is like hell on Earth.

Better fuel efficiency... maybe. If you're doing lots of very long journeys, I'd be inclined to put in 98RON - but they have to be long journeys at constant-ish throttle. I see a ONE mile per gallon improvement at best using 98RON compared to 95RON over a 250 mile journey - equivalent to a saving of less than a pound.

The best reason to put the occasional tank of 98 in is the cleaning additives they use. You'll get a quick flushing out of the injectors and allow you slightly improved fuel economy on the next few tanks of 95.
 
I also have a question - is the better Diesel fuel just as effective as the Petrol versions?
 
How do you mean?
 
You explained all of the improvements that 98RON Unleaded can do to an Unleaded car. Do the better Diesel Fuels (for example BP Ultimate Diesel) give diesel engines just as much improvement than using a 98RON fuel? Is it worth buying like 98RON is for most petrol cars?

Just wondering because I was thinking of advising my Dad to use the Ultimate Diesel fuel.
 
As far as I'm aware, it's the same deal, but what I know about greasel fuels can be written down on the back of an atom with a 12-bore shotgun.
 
G.T
I also have a question - is the better Diesel fuel just as effective as the Petrol versions?
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Diesel fuel is much less combustable then even 98 RON, since typical diesels have compression ratios of 14:1 to 24:1.

Edit: You AND Famine got those last two posts in before me! :grumpy:
 
Famine
but what I know about greasel fuels can be written down on the back of an atom with a 12-bore shotgun.
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Yeah, completely the same here...

With the many magazines I read, everything has been on Unleaded fuels. There wasn't even a sniff of Diesel fuels to be found... The only thing I DO know is that it's supposed to get rid of up to 37% of noise coming from the engine while cold.
 
Is that one of the 8.142% of statistics that isn't made up on the spot?
 
Cheers Famine 👍

I guess I'll give the engine a bit of a flush out with some Optimax or BP Ultimate and then just go back to the standard stuff.
 
Famine
Is that one of the 8.142% of statistics that isn't made up on the spot?
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Probably!

Oh well. It's 5p per litre more expensive than normal here, so I doubt I could convince him to buy it anyway.
 
you will get a little better performance from higher octane fuels you just need to advance the timing a little so you get the benefits IE advance it to you start to ping then back off a little
 
Meh, If your car doesn't require it, don't buy it, you'll be throwing away your money.

if your car knocks or pings, raise the octane 'till you can have it fixed...or, permanently, if it arises from a modification.
 
If your car has a high compression ratio it's recommended to use a higher octane. Otherwise theres not much gains in anything.
 
Famine summed it up great, but most cars on the road will not automatically advance timing for the new fuel. Many 'smart ECU' fuel injected cars reseting the ECU after using the new fuel will make the ECU find the sweet spot in timing again which could give some benefits, then when you go back to regular fuel will retard timing as soon as its knock sensors detects knocking/pre-detonation.

Overall it best to just use what manufacture recommends, but sometimes its nice to run some Premium for the extra cleaning agents they add to the fuel.

As for premium diesel well I'm not sure about that, I didn't even know it existed, they don't sell it here. I would imagine it would include cleaning agents like the unleaded does.

B_B_B
you will get a little better performance from higher octane fuels you just need to advance the timing a little so you get the benefits IE advance it to you start to ping then back off a little
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Yes advancing the may give some extra performance with the higher octane fuel, but I wouldn't bother,

*The gain you may get wont be all that great, to the point you would have trouble noticing. (No fast & furious blur screen style :p)
*Who can be bothered playing with timing for a small gain and some added risk.
*Don't forget not all pinging/detonating is audible from inside the car when driving, so increasing until you can hear ping then retard slightly may not mean you got rid of all the pre-detonation.
*You will need to run the higher octane fuel all the time now until you retard the timing back to what it was.
 
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