i was wondering if any of the garages are going to take legal action or will issue a response to it?

Interesting is they say that tesco's 99 was the best? i found it to be quite bad when i tried it, so kept with vpower instead.

OK so is it worth putting in super diesel into a 2.0 pd 140? I do a lot of miles and it costs a fortune at the moment, I could save 10% if it was not worth it

IMHO totally pointless and you'll get better MPG on standard derv.

If you fancy a bit of a cleaner engine try running with Millers Diesel Power Sport 4 assuming you're out of warranty.

V power diesel and ordinary diesel shouldnt make a difference really.

I used to use untimate diesel in company vans and it improved refinement at cruising speeds and made the engine sound as if it was revvving cleaner and free.

But petrol engines are a little more fussy some of them.

The VW FSI engines some of them need the higher RON petrol to run at their best apparantly.

But I wouldnt stick vpower/untimate unleaded into my Felly again as it doesnt have any noticable benefit. Better off sticking injector cleaner in every few years.

I'm not going to get into things like "additive packs", but higher octane petrol will only produce more power in an engine tuned (either deliberately or by a knock sensor) to run on it!

I've seen "super diesel" being sold as "higher citane index, makes less smoke", which is nice if you're worried about a smokey exhaust, but actually means the car will produce less power.

Yes a 1.6 Focus is designed to run on 95 oct,so what did Which hope to achieve using higher oct. fuel?? Some cars ,as said are designed to use higher oct Octy vRS is one,but it can be run on 95 with reduced output (so why buy a higher performance car if you are not going to use the full potential of it?

In last months Performance Tuner magazine there is a feature on Thorney Motorsport who have carried out a huge review of all the major fuels recently, with a surprising outcome,the best fuel was Tesco 99 oct. Must say I use it all the time and it works for me.

I find a very noticeable difference between 99 and 95 RON fuel in my GT. I have tweaked the timing though, but it doesn't pink on 95, it just feels more sluggish and less responsive. My usual is V-power, but I did try a tank of Tesco 99 a while back and didn't really notice any difference between that and V-power. Given that the Shell garages are almost always a good 4p a litre cheaper than the local Tesco, I just use V-power instead.

My 1.4 Saloon (100hp) sounds like a bucket of bolts when run on 95 Octy and performance is slightly down. So I use Ultimate (97 ron) or V Power (98.1 ron). Then, engine response much quicker and smoother, through the rev band.

I would speculate that there might be a solid reason behind this. In that the Fabia petrol engine was a well known propensity to wear out the piston rings, (The BBZ engine in mine being no exception - see my recent post) and the significant "Blow-by" associated with that, means that the mixture that is burnt can't be all that consistent in standard state and combustion temperature in a badly worn engine must be all over the place, with consequent pinking. If there is sensor feedback from each pot to the EMU, it must struggle to cope with the variant readings. In those circumstances perhaps the the higher octane and extra anti-pinking agents in the super petrols smooth out variations in combustion and enable the EMU to minimise the variants.

Nick

The Which report is cack if you look at it in a truely unbiased scientific way, it's poor journalism and I think premium diesel is a waste of money!!!

To be fair my opinion is:

- Posh derv is a waste of money.

- Posh petrol is a waste of money to your average car

- Posh petrol is useful where the car specifies it, is highly tuned or has a turbo/supercharger.

Label on the tank cap says 95 -98 Ron. But as said, it sounds and feels awful on 95. I think that's because the compression ratio is higher than the normal Fabia, your getting 100 BHP from a 1.4, when normally you'd only expect that sort of output from a 1.6. I think the engine experiences an earlier and more rapid onset of pinking, when the load on the engine exceeds the spec, if its fuelled with 95.

Nick

, on my old mk2 Octy vRS it would run like a dog on 95RON, but flew on V-Power / Optimax.

Interesting comment, In Ireland we really only have 95 octane fuel. I don't know why but it is a joke in this day and age Ireland can't have better fuel. Anyway my Octy 2 vRS runs quite well on 95 octane. With just a remapp and no other mods I still got the same results as remapped cars in the UK with the better fuel 98 upwards which was 237bhp.