(10-06-2014, 12:03 PM)Matt-Rallye Wrote:

(10-06-2014, 08:02 AM)ozonehostile Wrote: I only ever run my cars on texaco fuels petrol or diesel. I have noticed a difference running the gti6 on texaco 97 however, it just seems to run better and as bizzare as it sounds I'm sure I get slightly better mpg off it too

Don't really see using premium petrol as that much of an expense personally when compared to buying diesel, anything under 1.40 a litre feels like a bargain haha.

On the subject of different countries and what's available on their forecourts, ever seen how much choice French stations have?

I have also noticed after running my rallye on 97 (texaco) for the first time at FCS it starts better, idles sweeter and just generally seemed too pick up better and throttle response seemed alot sharper.

Mine only ever sees the morrisons cheapo fuel with a healthy dose of octane booster. Everything else is texaco.

(10-06-2014, 08:25 AM)MY95 Wrote:

(10-06-2014, 08:22 AM)RetroPug Wrote: I just run it on 95RON, gti-6s have knock sensors so it doesn't matter whether you use 95-99 in terms of ability to run properly.
You will get higher mpg with higher octances, but then they cost more, and I've never actually sat down and done the maths to work out precisely which is better value for money.

Thanks for the info, where do you get your standard 95 from then? Also have you tried the higher up stuff andnoticed much of a difference?

(10-06-2014, 05:33 PM)RetroPug Wrote:

(10-06-2014, 08:25 AM)MY95 Wrote:

(10-06-2014, 08:22 AM)RetroPug Wrote: I just run it on 95RON, gti-6s have knock sensors so it doesn't matter whether you use 95-99 in terms of ability to run properly.
You will get higher mpg with higher octances, but then they cost more, and I've never actually sat down and done the maths to work out precisely which is better value for money.

Thanks for the info, where do you get your standard 95 from then? Also have you tried the higher up stuff andnoticed much of a difference?

Typically shell but that's because there is one at the end of my street.

I have run all three of my gti-6s on shell's 95RON stuff, their V-power, tesco's fuels, various independant filling stations while on the road, BP's 95RON, ran on 95RON in Germany for 3 months as well.

Not once did I notice any perceptible difference.

The car has a knock sensor, so it will change the timing dependant on the octane of your fuel, as long as it is between 95 and a certain octane which I can't remember but is probably 99-103. I'm pretty sure the owner's manual says it somewhere. Higher octances within this range will give you more MPG but you've paid more per L and I'm unsure of precisely what the trade-off is. In any case, the car is designed to run on any and all fuels in that range. Maybe the running will be slightly smoother or you'll make +0.1 bhp but I can't say I've noticed.

I would be more concerned with the quality of fuel rather than the octane number, and some people argue that premium fuels are also purer and have better additives. I am sure that 95RON fuel from reputable petrol stations is of perfectly adequate quality though. It is worth bearing in mind that when the gti-6 was first produced fuels with a higher octance than 95 would have been a bit less common than they are now I'd have thought.

(13-06-2014, 11:44 PM)RetroPug Wrote: Does higher octance not also equal greater calorific content given higher octance fuels are longer chains of hydrocarbons?