If you had an S5 and it was UK you would say use Tesco Super wherever you can. Shell optimax as second choice and then if you really have to use BP or one of the other brand's super (but only fill up enough to get you to a shell or Tesco ).Thanks for the explanation Stimpyvan... It's a pity I haven't got a clue what you're talking about, being a bit crap when it comes to cars!
"Just put the best petrol in the car that you can rather that put in the cheap stuff."
I think that's what you are trying to say!
Actually makes as much of a difference, if not more. The S5's compression ration is "only" 11.0:1 compared to the V6's 12.5:1. The V8 is actually probably more tolerant of [email protected] fuel.If you had an S5 and it was UK you would say use Tesco Super wherever you can....
With the A5 i dont think it makes any difference.
This is very true. Also, how often the station replaces filters in the pumps makes a difference. If you ever notice that the pump you're using seems to be unusually slow, it probably is. Clogged filters will slow fuel delivery and the quality of the fuel you're pumping can be compromised.Although you should always buy from busy stations so the fuel is fresh. Especially in the case of Super.
I know what you're getting at, but it's misleading to say that without exception. For cars whose engine management systems are not designed to take advantage of higher octane fuel (i.e. they won't advance the timing enough), boosting the octane level does nothing. This doesn't apply to cars like the A5/S5, and most other high peformance cars, because they are tuned to be able to make the most out of high-test. But your typical 1997 Chevy Cavalier will derive ZERO benefit from filling it up with 93 octane.stimpyvan said:The higher octane fuel you put in your car, the better the engine will perform.
I doubt your Cavalier example would show any improvement with premium fuel. Like all modern cars, even the Chevy has a knock sensor, and will advance timing providing that detonation is not taking place. The compression ratio on a mainstream Chevy engine is not high enough that knock will occur under normal operating conditions when using mid grade fuel. Raising the octane level further will not result in an increase in performance, and as pointed out previously, because of the slightly lower energy content of high octane fuel, would probably result in a very small decrease in performance.I will nit-pick back about his second point (regarding a '97 Cavalier gaining any performance from higher octane fuel). Since I know next to nothing about 1997 Chevrolet products, I'll assume that the Cavalier's ECU won't automatically advance timing when higher octane fuel is used, however, if the owner of the car decided to run higher octane fuel exclusively, he could advance the timing himself.
So, Aerodave is correct that pumping high octane fuel into the car won't improve engine performance on its own, but advancing the ignition timing along with higher octane fuel will. The power gained from a couple of degrees of timing advancement can be substantial, depending on the motor.
120 RON? My God, didn't know it existed? Are your RONs the same as ours? - in the UK, anything over 99, i.e. 'Super' pump fuel is deemed specialist/racing and has a price tag to match. As an example, the Sunoco distributor I've recently purchased my measly 102 octane fuel from charges £700 for 200 litres of 109 RON fuel (and £100 for 25 litres!).....I'm not sure it can take full advantage of 120 ) since it's rather costly, but it gives me peace of mind to use some genuinely clean, high-octane fuel every once in a while.
Good God! I found a sunoco distributor up here and balked when he quoted me $10 (USD) a gallon for 104 octane. If I got my conversions close that comes to roughly £1.6 per a liter.Sunoco distributor I've recently purchased my measly 102 octane fuel from charges £700 for 200 litres of 109 RON fuel (and £100 for 25 litres!)
There are two methods how to count octane number, European is different than US. Research Octane Number (RON) and Motor Octane Number (MON).120 RON? My God, didn't know it existed? Are your RONs the same as ours? - in the UK, anything over 99, i.e. 'Super' pump fuel is deemed specialist/racing and has a price tag to match. As an example, the Sunoco distributor I've recently purchased my measly 102 octane fuel from charges £700 for 200 litres of 109 RON fuel (and £100 for 25 litres!)