Premium Unleaded V's Regular

[ukpuffy]

Does anybody notice any difference when they fill up with Premium instead of Regular. Is the performance that much better, does it return better miles per gallon, is it worth it?

[KebabMeister]

Premium (super) unleaded is 98 RON (octane) whereas regular unleaded is 95 RON (octane).  This basically means that 98 RON will give better performance and is fairly noticeable.  I can't imagine it returning more miles per gallon since I would assume it would be the same or more thirsty than 95 RON (plus when you usually notice a change in performance you usually take advantage of it so you may mentally start to put your foot down a bit more).

The cost of 98 RON is unjustifiable unless you have a high powered sportscar and you're rich!

[ukpuffy]

What about in a Astra 2.0 SRi, worth using Premium?

[Gef]

If your engine is designed to run on regular (most cars) then using premium is just a waste of money and will not affect performance of mpg at all.

[ianess]

 It's a bit like the "homeopathy v placebo" discussion in the news recently.  If you believe it works and you can afford it then so be it, but there is no proof that it is anything other than a waste of money.
Most of us have some sort of belief that we can't actually prove.  C'est la vie.

[Impret-Sir]

Ianess is not correct to say that there is no proof that higher octaine fuel will produce more power. And Gef is correct to say that if your engine management system is set for 'normal' unleaded then you will not notice any difference by using super unleaded. The facts are that certain cars, like my Impreza, are recommended to be run on super-unleaded by the manufacturers to get the most performance from them possible. I run mine on normal unleaded, and it costs me approximately 5 BHP or so, according to Subaru tuners. I can live with that , (its got plenty anyway!) and would rather have the savings I make in the cost of the fuel. Guys who regularly use super in their Subarus report a fuel saving of approximately 3/4 MPG, plus a recordable, (on a dyno) increase in power. The engine management chip in my engine can detect the lower octane rated fuel, and retards ignition timing, reduces maximum turbo boost etc to compensate, so no damage is done to the engine, hence the slight power drop. If I were to change to super unleaded it would take a while, usually reconed to be about two tank fuls for the chip to relearn the higher octane of the fuel, and adjust accordingly.

I would suggest that you would not notice any actual benifit in your astra, if it is otherwise standard, as it was set up from the factory to use standard unleaded.

[Carol Anne]

We still have my late father-in-law's Honda Legend which I used for a while this year, and the first thing I noticed when I took it out was a distinct rattling noise coming from underneath the car, which sounded like a buch of keys or something like that rattling, especially when I pressed the accelerator. I took it in to Kwik Fit who put it on the ramp but saw nothing, another mechanic reckoned it was the gearbox, then my neighbour suggested using premium unleaded and much to my amazement the rattling ceased. The reason ? the engine was 'pinking' on normal unleaded , this 'Lady' drank only champagne, and at twenty or so miles per gallon she has been in the garage ever since, and I hope not for much longer if my husband would pull his finger out and get rid !!

[c00ky83]

I noticed the difference by accident - about 7p per litre!  Won't make that mistake again.

[robber1]

Audi/VW cars can have an FSI engine which is designed to run on 98 RON. It will run on 95, but they say that performance and economy will fall. I have a 2 litre FSI Automatic, and on holiday I did 1400 miles and averaged 40mpg. This included driving around the docks getting totally lost! On one day it did 47mpg. At home, I get about 32mpg which is urban driving. Performance is good too. I wouldnt use it on an engine that wasnt built for it. Its damned expensive, so a big chunk of any gained fuel economy is lost.

[KebabMeister]

If you have a modern car with an engine management system (fuel injected) then it should automatically compensate the ignition timing and take advantage of using 98RON even if it was set up for 'normal' 95RON.  I say this because I would assume that 98RON would detonate at a different stage to 95RON because it's more refined and therefore the knock sensor would detect this and change the ignition timing.

I still wouldn't bother with it though; simply too expensive.